LABOKLIN Europe

New Diagnostic Tests for Fish and Reptiles

Laboklin | Bad Kissingen | NAH — Tue, 17 Mar 2026 10:54:51 +0000

Columnaris disease in koi and aquarium fish

The causative agent of columnaris disease is Flavobacterium columnare, a bacterium that plays a particularly important role in the ornamental fish trade. Flavobacterium columnare is a Gramnegative, rod-shaped bacterium measuring 5–12 ×

0.5 µm. It exhibits slow gliding motility but lacks flagella. Flavobacterium columnare has been detected in popular aquarium fish species such as neon tetra (Paracheirodon innesi), platy (Xiphophorus maculatus) and zebrafish (Danio rerio), as well as in pond fish such as koi (Cyprinus carpio). In principle, the pathogen can occur in all freshwater fish; however, outbreaks in pond fish are most common during the summer months when water temperatures are higher. Entry points for the pathogen are skin lesions. Infection is further promoted by poor water quality, high ammonia concentrations, elevated pH, and low oxygen levels. Initially, small whitish lesions develop around the mouth, fin margins, and scales, which resemble fungal growth as they enlarge. In scaleless fish such as channel catfish (Ictalurus punctatus), the infection begins as small bluish-grey necrotic lesions in the skin with a reddish inflammatory margin.

Microscopically, large numbers of F. columnare bacteria can be detected both in the centre and at the wound margins, with the edge often appearing to consist almost entirely of bacterial cells. In fish with scales, lesions may begin at the outer fin margins and spread inwards across the body, giving a saddle-like appearance. This is the origin of the term “saddleback disease”. Initially, degradation of the fin edges occurs, leaving the fin rays exposed.
The gills may also be affected. In such cases, the gill lamellae disintegrate from the tips towards the gill arches. In juvenile fish, excessive swelling of the gill epithelium and increased mucus production often lead to adhesion of the gill lamellae.
The consequence is reduced oxygen uptake, resulting in rapid respiratory movements.

Two clinical forms of columnaris disease can be distinguished. In the chronic form, white lesions enlarge slowly and fish die only after a prolonged course of disease. In the acute form, skin lesions spread within hours. Up to 50% of a fish population may die within 36 hours. In experimental infections in zebrafish, characteristic dorsal lesions have been observed as early as 24 hours post infection. Treatment must therefore be initiated rapidly.

Antibiotic treatment based on antibiogram results is generally possible. However, it should always be combined with optimisation of husbandry conditions. As the pathogen prefers an alkaline environment, lowering the pH to 6.8 may support treatment. For diagnosis, a swab is taken from affected body areas. This can be examined both by culture and by PCR. On Anacker–Ordal agar, F. columnare grows as pale yellow colonies at 18–30 °C (Fig. 1), with a tendency to adhere to the agar surface. At temperatures below 14 °C and above 33 °C, no growth occurs under culture conditions.

Cultural examination allows for antimicrobial susceptibility testing (antibiogram). The advantage of PCR lies in a shorter turnaround time and significantly higher sensitivity through DNA detection.
In addition, a small piece of affected fin tissue can be excised and examined microscopically. This reveals that many columnaris bacteria attach at one end and exhibit oscillating movements with the free end. At the margins of inflamed tissue areas, they aggregaggregate into column-like or cluster-like structures.

Emydomyces testavorans – a cutaneous fungus in turtles

Emydomyces testavorans is a keratinophilic fungus found in freshwater turtles. It belongs to the order Onygenales, which also includes other reptile-associated pathogens such as the genera Nannizziopsis, Ophidiomyces and Paranannizziopsis, all of which are primarily associated with dermatological diseases in various reptile species.

Emydomyces testavorans was first described in association with ulcerative shell lesions in fresh-water turtles in the western United States (Wood-burn et al. 2019). Since then, it has been detected in several species in North America (Woodburn et al. 2019; Davidson et al. 2025; Brunner et al. 2024; Fredrickson et al. 2024). To date, all research and reported detections of E. testavorans originate exclusively from North America, where the fungus has been identified in both zoological collections and wild freshwater turtle populations.

Clinically and pathologically, ulcerative shell lesions are most commonly described (Fig. 2), which may also affect deeper shell structures. In severe cases, epithelial inclusion cysts may develop and extend into deeper tissues; these can be visualised using computed tomography. In milder cases, pale areas on the shell may be observed. Chronic disease courses with slowly progressive shell changes have also been reported. Histologically, affected animals may show squamous epithelial metaplasia, hyperkeratosis, inflammation, and osteonecrosis (Woodburn et al. 2021).

Treatment is challenging and prolonged, and includes antifungal therapy, particularly terbinafine, as well as regular cleaning and disinfection of the environment. Effective disinfectants appear to include chlorine bleach, chlorhexidine, and accelerated hydrogen peroxide (Liszka et al. 2025). Diagnosis of Emydomyces testavorans is often difficult. The detection of characteristic inclusion cysts in the shell using computed tomography may indicate infection in severe cases. However, the fungus is difficult to culture and is often overgrown by other environmental or shell-associated fungi in culture. Superficial lesions frequently no longer contain viable fungal elements, and sampling from deeper layers can be challenging.

The recommended sample for pathogen detection by PCR is a combined swab from the oropharynx, cloaca, and shell. A dry swab (without transport medium) should be used. Recently, Laboklin has established a PCR assay for the detection of Emydomyces testavorans, making diagnosis of this pathogen possible in Europe. In recent months, several detections have already been made in different freshwater turtles in Germany, indicating that the pathogen is present in Europe and may cause clinical disease.

Dr. Martin Felten, Dr. Christoph Leineweber,
Dr. Rachel Marschang

Laboratory Diagnostic Evaluation of Body Cavity Effusions

Laboklin | Bad Kissingen | NAH — Mon, 16 Feb 2026 11:14:03 +0000

A body cavity effusion is defined as the accumulation of fluid in a body cavity, such as the thorax, abdomen, or pericardium. Animals with body cavity effusions present relatively frequently in clinical practice. Clinical signs may include dyspnoea, cardiac arrhythmias, limited auscultation of the heart, and an enlarged, often painful abdomen.
A wide range of diseases can be responsible. In addition to inflammation and infection, neoplasms or other space-occupying processes, as well as trauma, metabolic disorders, or cardiovascular diseases, may lead to the development of a body cavity effusion. For diagnostic evaluation, analysis of the effusion is therefore essential. Parameters assessed include macroscopic appearance, the proportion of different cell populations, physicochemical tests (e.g., total protein, albumin, triglycerides, bilirubin, Rivalta test), and cytological examination of the cells.

Sample Preparation

As a general rule, effusions should always be collected into two separate tubes. One tube should be an EDTA tube to prevent clotting of the sample.

In addition, a plain tube (e.g., an uncoated serum tube) should be filled. From the EDTA tube, the total nucleated cell count (TNCC) is measured, the erythrocyte content (PCV, haematocrit) is determined in cases of blood admixture, and smears are prepared for cytological examination.
The plain tube is used to determine clinical-chemical and physicochemical parameters. It is important that this tube is centrifuged promptly and that only the supernatant is used, in order to avoid skewing the results. For example, glucose concentration decreases over time depending on the cell count, as glucose is consumed by the cells or bacteria.
Bacteriological analysis can be performed either from the fluid in the plain tube or by taking a swab with medium from this tube. In any case, bacteriological testing can not be performed from the EDTA tube, as the EDTA coating has bactericidal effects.

For cytological examination, a smear should always be prepared directly in the clinic to ensure optimal cell preservation. Depending on the type of effusion, either a direct smear is sufficient (for cell-rich or blood-rich effusions; prepare the smear similarly to a blood smear) or cell concentration is required (for cell-poor effusions; smear with a stop line, sediment smear, or cytocentrifuged preparation).
For an external laboratory, it is essential to indicate whether a cell concentration was performed.
Only with this information can the cell count be accurately assessed, allowing correct classification of the effusion. A cell-rich direct smear has a different significance (e.g., exudate) than a cell-rich centrifugate (which may indicate a transudate). If samples are being prepared for shipment to an external laboratory, it is also important to include the preliminary report.
Relevant information are the signalment, clinical course, previous diagnostics, prior treatments, and the macroscopic appearance of the effusion if the fluid itself is not being sent.

Effusion Analysis – Macroscopic Findings

The assessment of colour and turbidity of the effusion can already provide useful informations (Table 1). However, the underlying cause of the effusion is generally not identifiable macroscopically.

Table 1: Broad classification of effusions based on macroscopic appearance

Diagnosis	Colour	Consistency
Hydrothorax / hydroabdomen / hydropericardium	clear	watery
Haemothorax / haemabdomen / haemopericardium	red	watery or coagulated
Serous inflammation	clear	watery, gelatinous
Fibrinous inflammation / chylous effusion	milky	watery, with flakes
Purulent inflammation	brownish	watery, creamy

It is particularly important that macroscopic assessment is performed immediately at the time of collection. In cases of blood admixture, an iatrogenic process is more likely if initially clear fluid is aspirated that later becomes reddish. In contrast, with haemorrhagic effusions, the fluid is red from the beginning.

Basic Parameters

The initial classification of effusions is based on protein concentration and cell count (Table 2).
If total protein measurement is not possible in the clinic, specific gravity can alternatively be determined using a refractometer. The total nucleated cell count (TNCC) can be measured either automatically using a haematology analyser with appropriate settings or manually using a haemocytometer. A semi-quantitative estimate is also possible from a smear during cytological examination (cell count per field × objective² = cells/ml). In specific cases, automated measurement should be avoided, for example, when a septic effusion is suspected (risk of contamination) or when the effusion is highly viscous or flocculent (risk of clotting). Using these parameters, effusions are classified as low-protein transudates, high-protein transudates, or exudates. In veterinary medicine, the term “modified transudate” is commonly used as a synonym for high-protein transudate. However, as it generally does not represent a modification during effusion formation, this term is increasingly avoided in more recent literature.

Table 2: Basic classification of effusions based on clinical-chemical parameters

	Cell Count (µl)	Protein (g/l)	Specific Gravity (g/l)
Low-protein transudate	< 1.500	< 25	< 1018
High-protein transudate	1.000–7.000	25–75	1018–1025
Exudate	> 5.000	> 30	> 1025

The classification described above is, however, very general and cannot reflect the full range of effusions and their underlying pathogenesis.
Further testing is often required. To differentiate between transudates and exudates, the simplified Light’s criteria can also be applied. An effusion is considered an exudate if the lactate dehydrogenase (LDH) concentration in the fluid exceeds two-thirds of the upper reference interval and the total protein in serum is greater than 4.0 g/dl. Classification using C-reactive protein (CRP, a major acute-phase protein) has also been described. The cut-off value in this case is 4 μg/ml. If this value is exceeded, the effusion is considered an exudate.

Specialised Investigations

For specific effusions, additional parameters are available (Table 3). In the case of a blood-rich, it is important to determine whether the blood was introduced iatrogenically during sampling or is originally present in the effusion. A haematocrit value of >3 % is considered indicative of a significant blood component.

The effusion haematocrit should be compared with the current peripheral blood haematocrit.
Haemorrhagic effusions can occur, for example, due to trauma, ruptured tumours (such as haemangiosarcoma), or coagulopathies (e.g., rodenticide poisoning).

For septic effusions, glucose and lactate can be assessed. Both parameters must be measured promptly after sample collection to avoid distortion of results. Glucose decreases due to consumption by cells or bacteria, while lactate increases as a product of anaerobic glycolysis. The differences between serum and effusion values are then calculated. Findings above the corresponding cut-offs (>20 mg/dl glucose, < -2 mmol/l lactate) suggest a septic effusion. Likewise, a lactate concentration >2.5 mmol/l is indicative of a septic process. However, neither parameter is specific, and the suspicion should be confirmed with additional tests. Bacteriological examination is also recommended in such cases.

For lymphocyte-rich effusions, triglyceride and cholesterol concentrations can help determine whether a chylous effusion is present. It is best to compare triglyceride concentrations in the effusion and serum (chylous effusion: effusion triglycerides > serum). Very high triglyceride concentrations in the effusion (>100 mg/dl) and a low effusion cholesterol/triglyceride ratio (<1) are also indicative of chylous effusions. It should be noted that lymphocyte-rich effusions are most commonly caused by heart disease (~70 %) rather than neoplasia (~25 %).

If a lymphoma is suspected, lymphocyte clonality can be assessed using PARR or immunophenotyping can be performed by flow cytometry. PARR is well suited to confirm lympho-ma, but a negative result does not rule it out; only a positive result is diagnostic. Immunophenotyping requires good cell preservation, so the sample must not be too old (see also LABOKLIN Aktuell, Issue 11/2024: “Leukaemias in Dogs and Cats”).
Thymidine kinase is a proliferation marker and can provide valuable information, particularly during follow-up, although it has not yet been validated for pleural effusions.

If an uroperitoneum is suspected, creatinine and potassium can be measured and compared in effusion and serum. In cases of suspected bilious effusion, bilirubin can be assessed accordingly.
If pancreatitis is suspected, lipase can be measured in the effusion (Table 3).

In cases of suspected feline infectious peritonitis (FIP), tests in addition to elevated total protein (>45 g/l) include the albumin/globulin ratio (<0.6) and the Rivalta test (positive). Ultimately, detection of the pathogen is recommended, which can be performed using coronavirus PCR from the effusion.

Table 3: Parameters for specific diagnostic questions

	Parameter	Cut-off / Result
Haemorrhagic effusion	Haematocrit / PCV	effusion > serum, > 3 % significant
Septic effusion	Glucose Lactate	serum – effusion = > 20 mg/dl Serum – Erguss = < -2 mmol/l or Lactate > 2,5 mmol/l
Chylous effusion	Triglycerides Cholesterol	triglycerides > 100 mg/dl or effusion > serum (3:1) or cholesterol/triglyceride ratio < 1
Lymphoma	Lymphocyte clonality (PARR) Flow cytometry Thymidinkinase	monoclonal proliferation predominance of a lymphocyte subpopulation (surface markers) proliferation marker (not validated for pleural effusions)
Uroperitoneum	Creatinine Potassium	effusion > serum (2:1) effusion > serum (1,4:1)
Bilious effusion	Bilirubin	effusion > serum (2:1)
Pancreatitis	Lipase	effusion > serum
FIP	Albumin, Globulin Rivalta test Coronavirus-PCR	A/G ratoio < 0,6 Rivalta test positive coronavirus-PCR from effusion or corresponding lesions (tissue) positive

Cytology

Semi-quantitatively, cytology itself can provide a rough estimate of cell count and protein content, allowing a preliminary classification of the effusion type. However, automated measurements are generally preferred. The main question addressed by cytology is usually which cells are present. In particular, cytology is used to search for tumour cells or intracellular microorganisms. It also allows microscopic differentiation of leukocytes (e.g., increased neutrophils or eosinophils, lymphocytes, macrophages).

If a septic effusion is suspected, cytology is advantageous for several reasons: to estimate the cell count (these samples should not be measured in automated analysers due to contamination or clotting risk), to detect intracellular pathogens (differentiation from secondary contamination), and to assess the morphology of neutrophils (degenerative changes). Cytological detection of filamentous bacteria (e.g., Nocardia spp., Actinomyces spp.) can also be diagnostically significant, as these bacteria require special culture requirements. Additinally, cytology can sometimes provide information on chronicity. For example, in haemorrhagic effusions, erythrophagocytosis can be observed within a few hours, whereas siderophages typically appear after approximately 2–4 days. Both are indicators of red blood cell breakdown. The presence of platelets without signs of red cell degradation suggests an iatrogenic or peracute process.

Certain cytological structures can further indicate the origin of the effusion. In an uroperitoneum, urine crystals may be present; in a bilious effusion, bilirubin crystals or bile can be detected.
Mesothelial cells may be present in any effusion. In chronic effusions / chronic inflammation, these cells can exhibit marked dysplasia, which makes a morphological differentiation of mesothelial and carcinoma cells challenging or in some cases impossible. In neoplastic effusions, it is important to note that the primary tumour does not necessarily reside in the same compartment. Moreover, only a positive cytology result is definitive, as not all neoplasms shed tumour cells into the effusion.

Conclusion

With only a few parameters (macroscopic findings, total protein, and cell count), it is generally possible to perform a rough classification of the effusion already and thus narrow down the differential diagnoses. However, additional investigations are often required depending on the suspected diagnosis. This article summarises the most commonly used parameters (see Tables 1–3). Cytological examination provides further specific information and is particularly important for septic and neoplastic effusions. It can also provide valuable information in cases of hemorrhagic effusions, uroperitoneum, and bilious effusions.

If only a small volume of material can be obtained, cytology is always recommended, as it allows at least a semi-quantitative basic classification in addition to the morphological assessment.

Dr. Katrin Törner

Our Services on This Topic

Cytology / Cytology Requiring Increased Effort

Body Cavity Effusion Analysis (Cytology, total protein, cell count, Rivalta test [cat], cholesterol, triglycerides, albumin/globulin ratio)

Body Cavity Effusion FIP Cat (Cytology, total protein, cell count, Rivalta test, albumin/globu-lin ratio, coronavirus PCR)

Acute-Phase Proteins in Dogs and Cats – Current Insights and Clinical Relevance

Laboklin | Bad Kissingen | NAH — Fri, 30 Jan 2026 12:07:11 +0000

The acute-phase response (APR) is an early systemic reaction to inflammatory stimuli, infections, and tissue damage. The synthesis of specific acute-phase proteins (APPs) in the liver is regulated by proinflammatory cytokines (IL-6, IL-1β, TNF-α), with their concentrations in the blood rising or falling during an APR. APPs are valuable markers for detecting and monitoring the progression of inflammatory processes as well as neoplastic diseases. The APR occurs significantly earlier and more specifically than changes in leukocyte counts.

APPs are classified based on the magnitude of their response into major (10–100-fold increase), moderate (2–10-fold increase), and minor (<2-fold increase).
Measurement of major APPs is particularly useful for early diagnosis and monitoring of diseases associated with an APR. In dogs, C-reactive protein (CRP) is the primary major APP, whereas in cats, serum amyloid A (SAA) predominates. Haptoglobin (Hp) and α1-acid glycoprotein (AGP) are considered moderate to minor responding APPs. Albumin, transferrin, and paraoxonase are negative APPs, whose concentrations typically decrease during an acute-phase response. The behaviour of the respective APPs during the APR is summarised in Table 1.

Dogs – CRP as the Gold Standard

As a major APP, C-reactive protein (CRP) increases within 4–24 hours following the triggering insult, rising up to 50–100-fold, reaches its peak after 1–2 days, and declines rapidly with effective therapy.
Due to this dynamic behaviour, CRP is particularly well suited for early detection, monitoring disease progression, and assessing therapeutic success.

Elevated CRP levels are observed in a wide range of inflammatory and immune-mediated processes, including bacterial infections, parasitic diseases, autoimmune disorders, neoplasms, and post-traumatic or postoperative changes. In dogs with acute Babesia canis infection, CRP shows a strong correlation with clinical severity and haematological parameters.

Within the framework of antimicrobial stewardship, it has been shown that antibiotics can be discontinued once clinical improvement is observed and CRP concentrations have returned to normal, which significantly shortens the treatment duration for many diseases.

In systemic mycoses, such as pulmonary coccidioidomycosis, CRP in combination with haptoglobin (Hp) also demonstrated predictive value for remission. However, CRP can be elevated in the absence of inflammation, for example during extreme physical exertion or pregnancy, so its interpretation must always take the clinical context into account.

Acute-Phase Index (API) – a Combined Marker

Recent research has combined positive APPs (CRP, Hp) and negative APPs (albumin, optionally PON-1) into an acute-phase index (API). This index reflects the overall activity of inflammation. Dogs with malignant tumours and a high API had a significantly poorer prognosis.

Table 1: Overview of changes in acute-phase proteins and leukocyte counts over time following an inflammatory stimulus in dogs and cats.

Time after Inflammatory Stimulus	Dog – e.g., CRP, SAA	Dog – Leukocyte Count	Cat – e.g., SAA, AGP	Cat – Leukocyte Count
0–6 h	slight increase at the start (hepatic synthesis begins within a few hours)	usually still within the reference range	slight increase at the start	usually still within the reference range
6–12 h	marked increase measurable	first tendency to rise possible, often still borderline	marked increase measurable	first tendency to rise possible, often still unremarkable
12–24 h	strong increase, values usually clearly pathological	leukocytosis or leukopenia often visible	strong increase, clearly pathological	more frequent leukocytosis, sometimes stress leukogram
24–48 h	peak of APR – highest concentrations	further increase or plateau of leukocytes	peak of APR	further increase or plateau of leukocytes
2–5 days	beginning decline if inflammation is controlled	leukocytes often still elevated, slowly decreasing	decline with clinical improvement	leukocytes often still altered, normalising more slowly
> 5 days	return to or near reference range in resolving inflammation	normalisation, but may take longer with chronic processes	similar to dogs	similar to dogs

APR = acute-phase response, CRP = C-reactive protein, SAA = serum amyloid A, AGP = α1-acid glycoprotein

In chronic inflammatory diseases, such as canine leishmaniasis, CRP and Hp remain persistently elevated, while albumin and transferrin often decrease. Changes in the API correlate closely with treatment response and disease activity. Persistently high values indicate residual activity, co-infections, or treatment failure.

Cats – Focus on SAA and AGP

In cats, the dynamics and significance of APPs differ considerably from those in dogs. Serum amyloid A (SAA) is the most important major APP, while α1-acid glycoprotein (AGP) has particular diagnostic value in feline infectious peritonitis (FIP).

Serum Amyloid A (SAA)

SAA responds very early and sensitively, reaching high concentrations quickly, making it suitable for both early diagnosis and prognostic assessment. A rapid decline indicates a good response to therapy, while a stagnating value suggests persistent inflammation or secondary infection. Modern turbidimetric assays using monoclonal antibodies provide high diagnostic precision. Further studies demonstrate the usefulness of SAA, especially in bacterial infections such as pyelonephritis.

Alpha-1-acid Glycoprotein (AGP)

AGP is a moderately rising APP with high clinical relevance for FIP (Fig. 1). Elevated AGP serum levels support the presumptive diagnosis when interpreted alongside other findings. In particular, during antiviral therapy, AGP shows dynamic changes.

Haptoglobin (Hp)

In both dogs and cats, Hp is a moderate acute-phase protein synthesised in the liver. Its primary biological function is the high-affinity binding of free haemoglobin (Hb) from lysed erythrocytes, which reduces oxidative tissue damage and prevents the loss of Hb-bound iron. During acute inflammatory processes, both species exhibit a less pronounced and delayed increase in Hp concentration compared with major acute-phase proteins such as SAA or CRP. As in other mammals, intravascular haemolysis can lead to a decrease in haptoglobin concentration because the protein is rapidly consumed through binding large amounts of free haemoglobin.

Negative Acute-Phase Proteins

Albumin
Albumin decreases due to the redistribution of amino acids for the synthesis of positive APPs and increased capillary permeability. It is a valuable indicator of systemic inflammation but must be interpreted in the context of hydration status, protein loss, and liver function. In dogs, albumin is included in the calculation of the acute-phase index (API).

Transferrin
Transferrin, an iron-binding transport protein, decreases during the acute-phase response to reduce iron availability for microorganisms. In dogs, a marked decrease in transferrin has been observed during bacterial infections. In cats, a significant decline has also been documented in cases of chronic inflammation.

Acute-Phase Proteins in FIP

Feline infectious peritonitis (FIP) is an inflammatory disease that is generally associated with an increase in acute-phase proteins. Studies have shown that measuring AGP in effusions is the most informative method for distinguishing between cats with and without FIP. Different cut-off ranges with varying sensitivity and specificity have been defined (Table 2). Some of these cut-offs, for example in Helfer-Hungerbühler et al. (AGP > 2927), exhibit high specificity (97 %) and can therefore be strongly indicative of FIP. However, due to the relatively low sensitivity (54 %), almost half of the cats with FIP may not be detected. It should also be noted that APPs can increase in other diseases. Cats with a septic abdomen or disseminated neoplasms often show AGP concentrations similar to those observed in cats with FIP. Therefore, complementary cytological and bacteriological examinations are important to exclude differential diagnoses.
Measurement of AGP alone is insufficient for a definitive diagnosis and should be considered as one of many components in the diagnostic process.
AGP may also play an important role in therapy monitoring for cats with FIP. During treatment, AGP gradually decreases, although more slowly than SAA. This is likely due to the longer half-life of AGP, which means that AGP concentrations on day 2 of FIP therapy can be higher than before treatment began. A significant decline in AGP was observed from day 7 after the start of therapy. By day 28, AGP levels were within the normal range in almost all cats (Helfer-Hungerbuehler 2024: 17 of 18 cats, Zuzzi-Krebitz 2024: 37 of 39 cats), making it a reliable parameter for monitoring treatment success. In contrast, SAA showed a significant decline already by day 2, and most cats reached (almost) normal SAA concentrations within 4–7 days. Addie and colleagues (2022) use AGP as a marker to differentiate between remission and recovery. Recovery refers to complete healing from FIP, while remission is defined as an intermediate stage between recovery and death, still carrying a risk of relapse. Cats that fully recovered showed AGP values within the normal range, whereas cats in remission exhibited elevated AGP levels.
Therefore, a rise in AGP could also indicate a potential FIP relapse.

Table 2: Overview of recent publications on the use of AGP. Measured median values (including range) in cats with FIP compared with cats without FIP, defined cut-off values, and their sensitivity and specificity.

Study	Acute-Phase-Protein	Median Value in Cats with FIP (Range)	Median Value in Cats without FIP (Range)		Cut-Off	Sensitivity (%)	Specificity (%)
	Serum
*Hazuchova* *2017*	AGP (µg/ml)	2900 (960-5040)	690 (120-4500)		2260	85	90
	SAA (µg/ml)	98,5 (1,3-163,4)	7,6 (0,1-163,8)		97,3	55	87
	Hp (mg/ml)	2,0 (2,0-9,0)	1,8 (0,0-2,0)		2,0	55	82
	Effusion
	AGP (µg/ml)	2570 (1300-5760)	480 (190-3800)		1550	93	93
	SAA (µg/ml)	80,4 (0,1-207,4)	0,1 (0,1-182,7)		43,6	71	91
	Hp (mg/ml)	2,2 (0,1-9,3)	0,8 (0,1-2,5)		2,1	79	87
	Serum
*Helfer-* *Hungerbuehler* *2024*	AGP (µg/ml)	2954 (200-5861)	healthy	sick	2531	61	79
	AGP (µg/ml)	2954 (200-5861)	235 (78-616)	1734 (305-3449)	2927	54	97
	Effusion
	AGP (µg/ml)	2425 (343-5611)	560 (83-3950)		1686	71	89
	Serum
*Romanelli 2024*	AGP (µg/ml)	1986 (405-4428)	296 (165-4254)		707	80	80
					>4099	–	100
					<438	100	–
	Effusion
	AGP (µg/ml)	1717 (549-3166)	233 (103-4099)		990	75	73
					>4254	–	100
					<296	100	–

Dr. Ruth Klein, Katharina Buchta

Equine Sarcoidosis

Laboklin | Bad Kissingen | NAH — Mon, 22 Dec 2025 11:07:01 +0000

Introduction

Equine sarcoidosis (ES) represents an unusual idiopathic disease in horses, characterised by granulomatous inflammatory processes of the skin and/or other organs. Similar histological changes have also been described in dogs, humans, and cattle. The exact pathogenesis remains unclear; however, an aberrant immune response to an unidentified infectious agent or an allergen is suspected. Clinically, three forms of ES are distinguished: generalised sarcoidosis, partially generalised sarcoidosis, and localised sarcoidosis.

Clinical Presentation

Generalised equine sarcoidosis (GES) is also referred to as “idiopathic, generalised or systemic granulomatous disease” or “wasting syndrome.” Clinically, affected horses may show loss of appetite, weight loss progressing to cachexia, and fever, with granulomatous inflammatory processes occurring in multiple organs as tumour-like masses. The lungs are most frequently involved; however, other organ systems such as the gastrointestinal tract, liver, spleen, or lymph nodes may also be affected. Further clinical signs primarily depend on the organs affected. Most horses with generalised sarcoidosis exhibit skin involvement in addition to visceral changes (Fig. 1).

In contrast to veterinary medicine, in human medicine 90 % of patients with sarcoidosis have pulmonary involvement, and 30 % show cutaneous manifestations, particularly around the nose and mouth.

No sex or breed predisposition has been identified in horses to date. Horses of any age can be affected, although the disease is rarely seen in animals younger than three years. The prognosis for GES is poor to guarded, as the condition usually does not respond to therapy and progressive deterioration of general health often necessitates euthanasia.

Localised equine sarcoidosis (LES) represents the most frequently occurring form of the disease (own observation). Clinically, LES is characterised primarily by a scaly or crusted exfoliative dermatitis.

Less commonly, solitary or multiple tumour-like skin nodules may be observed. The distal limbs are most often affected, although other body regions can also be involved. Variable hair loss and oedema may also occur (Sloet van Oldruitenborg-Oosterbaan, 2013). Skin lesions can be painful or, occasionally, pruritic. Involvement of the coronary band may be accompanied by laminitis and lameness.
In cases of LES, lifelong immunomodulatory therapy is often required to induce remission of skin lesions and to maintain it thereafter.
In partially generalised equine sarcoidosis, multiple or more extensive skin areas are affected, and patients frequently present with lymphadenopathy. Progressive involvement of additional organ systems with development into GES is possible. The prognosis for most horses is similarly poor to that of GES.

Pathogenesis

The pathogenesis of ES remains unclear. It is, however, thought to involve an aberrant or excessive immune response to an infectious agent or an allergen. To date, attempts to identify a definitive causative pathogen in tissue samples using molecular diagnostics (e.g., PCR) or special staining techniques have been unsuccessful. Interestingly, poisoning with Vicia villosa (hairy vetch) can lead to clinical and histological changes similar to those observed in GES.

Generalised or systemic granulomatous diseases have also been described in dogs and humans, and their pathogenesis is similarly unresolved. In human medicine, it is hypothesised that antigenic stimulation of CD4+ T-lymphocytes leads to cytokine release, macrophage accumulation, and granuloma formation. Potential antigenic triggers discussed include mycobacteria, Corynebacterium acnes, serum amyloid A, non-infectious environmental antigens, and autoantigens (e.g., vimentin).

In humans, pulmonary sarcoidosis has been associated with inhalation of silica and metal particles in certain occupational groups (e.g., firefighters, rescue workers). Sarcoid-like granulomas have also been linked to tattoos, antiperspirants containing aluminium–zirconium complexes, and cosmetic procedures such as vitamin C microneedling. Furthermore, granulomatous skin lesions in children with primary immunodeficiencies have been associated with persistent rubella antigen following vaccination.

It is therefore conceivable that, in horses, inert antigens that are difficult for macrophages to phagocytose, or immunological abnormalities, may similarly contribute to the pathogenesis of sarcoidosis.

Diagnosis and Diﬀerential Diagnosis

As other inflammatory skin conditions, such as pemphigus foliaceus, coronary band dystrophy, dermatophilosis, or multisystemic eosinophilic epitheliotropic disease (MEED), can clinically resemble sarcoidosis, a histopathological examination of multiple skin biopsies is recommended for the diagnosis of LES. These typically reveal, in addition to epidermal hyperplasia and hyperkeratosis, a pronounced diffuse granulomatous dermatitis extending from the superficial to the deep dermis (Fig. 2). Macrophages and multinucleated giant cells dominate the inflammatory response, with lymphocytes, plasma cells, and neutrophilic granulocytes also present.
Special stains for fungi and bacteria, including acid-fast organisms, are negative.

Treatment and Prognosis

Patients with generalised and partially generalised sarcoidosis generally show little or no adequate response to immunomodulatory therapy. In most horses with generalised or partially generalised sarcoidosis, euthanasia is often performed due to poor general condition and progressive weight loss leading to cachexia.

Horses with localised sarcoidosis show a variable response to immunomodulatory therapy. In many cases, remission of skin lesions can be achieved with glucocorticoid treatment. However, long-term maintenance therapy is often required to prevent recurrence or progression of skin changes (Wimmer-Scherer, 2024).

Long-term glucocorticoid therapy can be associated with an increased risk of laminitis, particularly in patients with concurrent conditions such as dysfunction of the pituitary pars intermedia (PPID) or equine metabolic syndrome. For patients showing insufficient response to glucocorticoid therapy, treatment with the folate antagonist methotrexate may be beneficial. A small proportion of horses with localised sarcoidosis may experience spontaneous remission.

Ines Hoﬀmann, Barbara Gruber

Allergen-specific Immunotherapy in Horses: Causes of Early Discontinuation and Strategies to Improve Outcomes

Laboklin | Bad Kissingen | NAH — Fri, 19 Dec 2025 13:01:55 +0000

Allergen-specific immunotherapy (ASIT, hyposensitisation) represents the only causal treatment for allergic diseases in horses. These allergies can manifest as cutaneous signs, including pruritus and urticaria (atopic dermatitis and sweet itch), or as respiratory symptoms, such as equine asthma. In some cases, headshaking may also be associated with allergic reactions. The most common causative allergens are environmental – including pollens, house dust or storage mites, and moulds – as well as insect allergens.

Allergies cannot be cured, but only managed, and require lifelong treatment. ASIT is the only therapeutic option that acts causally on the disease process. It is an effective and safe treatment, with successfully treated horses showing markedly reduced symptoms or even becoming completely symptom-free. By administering an extract containing the relevant allergens, the immunological response to environmental allergens is modulated. The conventional ASIT protocol consists of subcutaneous injections of the extract, initially at short intervals that are gradually extended, with increasing doses according to the protocol, over a period of weeks to months (initial treatment, or induction phase). This is followed by maintenance treatment, during which a constant amount of the extract is administered at longer intervals (typically 1 ml every 4 weeks). According to the guidelines of the International Committee on Allergic Diseases of Animals (ICADA), ASIT should be continued for at least 12 months before evaluating clinical success. If a horse responds favourably to ASIT, treatment should ideally be continued long-term, potentially for life.

Survey-based Study at Laboklin

The aim of the study was to identify the reasons for discontinuation of ASIT in horses during or after the induction phase (initial treatment, starter set).
The induction phase lasts approximately six months, which is considerably shorter than the recommended 12-month period for assessing the response to therapy.

Horses were selected from the ASIT treatment order lists of the Laboklin laboratory for the years 2021–2023, specifically those for whom no further ASIT treatments were ordered after the starter set. Of 4,271 initial treatments, 1,475 cases (34.5 %) did not receive any follow-up treatments.
To determine the reasons for discontinuation of ASIT, the treating veterinarians were contacted using written questionnaires. They could select one or more possible reasons. The collected data were analysed descriptively.

Reasons for ASIT Discontinuation

A total of 171 responses reporting 204 reasons for why no follow-up ASIT treatment was ordered after the initial treatment were analysed. Patients who did not receive further ASIT due to death (n = 15) were excluded from the analysis.
The horses included in the study exhibited the following symptoms: asthma (n = 68, 39.8 %), pruritus (n = 40, 23.4 %), urticaria (n = 3, 1.8 %), headshaking (n = 3, 1.8 %), or a combination of these symptoms (n = 31, 18.1 %). In 26 horses (15.2 %), the specific symptoms were not reported (Fig. 1).

The most common reasons for discontinuation of ASIT (Fig. 2) were loss of contact with the owner (n = 55, 27 %), lack of owner compliance (n = 40, 19.6 %), insufficient treatment response (n = 39, 19.1 %), or a good treatment response (n = 27, 13.2 %).

These four reasons accounted for over 80 % of treatment discontinuations. Other reasons included cost or sale of the horse (each n = 13, 6.4 %), adverse effects (n = 4, 2 %), and lack of knowledge regarding continuation of ASIT (n = 4, 0.5 %).

ASIT was also discontinued due to symptom improvement following a change of stable or optimisation of management (n = 7, 3.4 %) or a dietary change (n = 1, 0.5 %). In three horses (1.5 %), the induction phase had not yet been completed due to protocol adjustment, and in one horse (0.5 %), ASIT was continued but the ASIT manufacturer was changed.

In 116 questionnaires, it was reported that ASIT was administered according to the manufacturer’s protocol, while in four horses the protocol was individually adjusted. No additional symptomatic therapy was given in 93 horses; 11 horses received mucolytics alongside ASIT, 15 underwent inhalation therapy with glucocorticoids and bronchodilators, and six patients were treated with systemic glucocorticoids. In eight horses, it was reported that symptoms worsened again after ASIT was discontinued.

How Can ASIT Discontinuation Be Reduced and Treatment Success Optimised?

Induction treatments usually last for six months, which is considerably shorter than the recommended 12-month period for evaluating therapeutic success.

It can take up to a year for the full clinical benefit of ASIT to become apparent. In this Laboklin study, follow-up treatment was not ordered for over one third of initial treatments, resulting in premature discontinuation of ASIT after the induction phase.

Loss of Contact with Owners and Lack of Owner Compliance
The most common reasons for ASIT discontinuation were loss of contact between veterinarian and owner (27 %) and lack of owner compliance (19.6 %), together accounting for nearly 50 % of all discontinuations. In a Laboklin study on ASIT discontinuation in dogs, these were likewise the most frequently reported reasons. Owner compliance – the cooperation of the owner in implementing the recommended therapeutic measures – is a crucial factor for treatment success. Owners should be thoroughly informed about the treatment protocol, duration of therapy, the delayed onset of ASIT effects, and the expected costs, in order to align their expectations appropriately. Continuous communication is key to ensuring good owner compliance, particularly during the first year of therapy. Regular check-ups or telephone contact with owners not only maintain communication but also ensure continuous monitoring of the patient.

Treatment Success Lower than Expected
The third most common reason for ASIT discontinuation was insufficient therapeutic response (19.1 %). This was often reported in combination with poor owner compliance. Due to the delayed onset of ASIT effects, treatment success should be evaluated no earlier than one year after initiation.
Discontinuation of ASIT due to perceived lack of efficacy after the induction phase represents an issue of owner education, as these horses were prematurely classified as non-responders.
Veterinarians should clearly communicate the delayed onset of ASIT effects in order to manage owner expectations and prevent premature discontinuation during the first year of therapy.
In the current study, 93 horses reportedly did not receive any additional therapy, while only 15 horses were treated symptomatically during the induction phase of ASIT to alleviate allergic signs. Symptomatic treatments – such as glucocorticoids, antihistamines, bronchodilators, and mucolytics (in cases of equine asthma) – are often necessary during the first months of ASIT to rapidly reduce clinical symptoms until the effects of the immunotherapy take hold.
This approach is also an important factor in improving owner compliance. The duration and dosage of medications should be kept as low as possible. Symptoms should be reduced but not entirely suppressed, as complete suppression may obscure the need for protocol adjustment.
It is also important to correctly define treatment success. ASIT is considered successful if treated horses show an improvement of more than 50 % in clinical symptoms, or if the need for additional symptomatic medications can be reduced by more than 50 %. Before a horse is classified as a non-responder, it should be carefully evaluated whether there is truly no improvement. This requires precise documentation of the frequency of allergic episodes, as well as the duration and dosage of any additional symptomatic therapy. In this study, four respondents reported that ASIT was discontinued due to insufficient effect, but symptoms subsequently worsened after cessation. In these cases, it can be assumed that ASIT did provide clinical improvement that was not adequately documented, leading to the erroneous classification of these horses as non-responders.
The average success rate of ASIT in horses, according to a review by Herrmann et al. (2023), was 75 % for equine asthma, 88 % for urticaria, 59 % for pruritic dermatitis, and 36 % for sweet itch (ASIT using insect allergens only). Limited data are available regarding the efficacy of ASIT for allergy-in-duced headshaking; one study reported good to very good responses in five of the six horses included.
The reason why horses treated solely with insect allergens show lower success rates is not fully understood. One possible explanation is that, due to the simultaneous presence of different allergens, it is clinically difficult to distinguish between environmental pollen allergies and sweet itch (insect bite hypersensitivity). Many horses are polysensitised, and in these cases, additional allergens besides insects should be included in ASIT. Another theory is that insect allergens in ASIT may induce a weaker immune response compared with other allergens. This could be related to the fact that only whole-body extracts are currently available for ASIT, whereas treatments using pure insect salivary proteins might be more effective. This hypothesis is supported by studies using recombinant allergens in ASIT. A recent study by Graner et al. (2024) treated horses with ASIT consisting of recombinant Culicoides allergens. Clinical response was significantly higher than in the placebo control group, with almost 90 % of treated horses showing at least a 50 % improvement in symptoms in the second year of treatment.
The duration of the disease may also influence the success rate of ASIT. Hunsinger (2003) reported that horses treated with ASIT within two years of the onset of allergic symptoms responded significantly better to therapy. In horses with sweet itch, the success rate of ASIT was 75 % when treatment was initiated within the first two years after disease onset. This rate decreased considerably when the start of ASIT was delayed.
Another measure to optimise treatment success may be the individual adjustment of the protocol regarding injection volume and/or treatment intervals. In this study, protocol adjustment was reported in only four horses; all other patients were treated according to the manufacturer’s protocol.
Continuous patient monitoring is necessary to identify the need for protocol adjustment.

Discontinuation despite successful response
The fourth most common reason for stopping ASIT (13.2 %) was clinical improvement in the treated horses, leading to interruption of therapy. Most patients require long-term, often lifelong treatment to maintain control of allergic symptoms. Experience shows that symptoms typically recur after ASIT is discontinued. This was also observed in the present study in two patients whose ASIT was not continued due to marked improvement. Restarting ASIT can be demanding, often requiring repeated allergy testing, initiation of a new induction phase, and in some cases, a less favourable therapeutic response. Therefore, it is generally recommended not to interrupt ASIT in responders and to inform owners of the need for ongoing treatment. If clinical improvement is stable over several years during the maintenance phase, injection intervals may be gradually extended up to eight weeks.

Costs
In this study, costs were cited as the reason for ASIT discontinuation in 6.4 % of cases. For owners, the expenses associated with ASIT during the first year—including allergy testing and regular veterinary check-ups—may appear high.
However, in the long term, ASIT is considerably more cost-effective than purely symptomatic therapy, which can be very expensive in horses. Poorly controlled allergic horses often require more frequent veterinary visits, higher doses of symptomatic medications, and additional diagnostic or therapeutic interventions to manage potential side effects of these treatments. Providing this information can help motivate owners to continue ASIT throughout the first year of treatment and, during the maintenance phase, even in cases of moderate clinical response.

Side effects
In general, ASIT can be considered very safe in horses. In the present study, ASIT was discontinued due to adverse effects in four horses (2 %). In all cases, allergic symptoms worsened following the injections; additionally, one horse developed diarrhoea and another experienced circulatory problems. Worsening of allergic signs immediately after injections is one of the most common adverse effects, which was also observed in this study.
If this side effect occurs, the allergen extract dose should be reduced and the induction protocol individually adjusted. The importance of continuous communication between veterinarians and owners should be emphasised with regard to adverse effects. Owners should carefully observe their horses’ reactions to injections and immediately report any issues to the treating veterinarian to allow appropriate adjustments to the ASIT protocol.
The Laboklin team is available for consultation regarding protocol modifications.
Anaphylactic reactions (urticaria, angioedema, respiratory distress, circulatory collapse) are very rare. One horse in the current study experienced circulatory problems, leading to discontinuation of ASIT. The most common adverse effect during the induction phase is a self-limiting local reaction at the injection site; however, this was not cited as a reason for treatment discontinuation.

Conclusion

In summary, ASIT represents an important component of the multimodal management of allergic horses and is a lifelong therapy that requires close collaboration between owners and veterinarians. The first year of treatment necessitates intensive monitoring and constitutes the critical period for achieving therapeutic success. The most common reasons for discontinuation of ASIT are loss of contact with owners, poor owner compliance, and overly high expectations regarding rapid treatment effects. Improved education and communication, regular check-ups, and strict adherence to ASIT guidelines can increase the number of horses that respond successfully to ASIT and derive long-term benefit from the therapy.

Dr. Elisabeth Reinbacher

Our Services for Equine Allergies

Screening tests

Main tests for allergen differentiation (seasonal allergens, perennial allergens, insects, feathers/ hair/dander, feed)

Screenings (allergy profiles – skin, allergy profile – respiratory)

PAX complete (environmental allergens and/or food)

Allergen-specific immunotherapy (ASIT)

Expert Panel on Cushing’s Syndrome

Laboklin | Bad Kissingen | NAH — Wed, 03 Dec 2025 09:31:09 +0000

The Laboklin Expert Panel has now become a well-established institution. Three to four times a year, it addresses a broad range of clinically relevant questions. For the topic of Cushing’s syndrome, specialists in endocrinology, pharmacology, and surgery shared their expertise, drawing on both current clinical experience and the latest scientific evidence.

The experts participating in the panel were:
Prof. Dr Wolfgang Bäumer, Dipl. ECVPT, Director of the Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Free University of Germany; Prof. Dr Nadja Sieber-Ruckstuhl, Dipl. ACVIM and ECVIM-CA, Head of Endocrinology, Small Animal Clinic, University of Switzerland; PD Dr Astrid Wehner, Dipl. ECVIM-CA, Senior Lecturer in Internal Medicine with a focus on Endocrinology, LMU Germany; PD Dr Florian Zeugswetter, Head of the Endocrinology Department, University Small Animal Clinic, Austria; Dr Pieter Nelissen, Dipl. ECVS, RCVS Specialist, Managing Director and Chief Surgeon, Frontier Small Animal Specialists, Germany.

The introduction addresses the current nomenclature of Cushing’s syndrome. PD Dr Florian Zeugswetter explains that the European Society of Veterinary Endocrinology (ESVE), within the framework of the “ALIVE” project, has agreed on a standardised terminology. Disorders caused by an excess of glucocorticoid-active substances are therefore referred to as Cushing’s syndrome (CS). A distinction is made between iatrogenic forms and naturally occurring CS.
Naturally occurring CS can be further classified into ACTH-dependent and ACTH-independent forms.
ACTH-dependent variants include the classic pituitary-dependent CS, whereas ACTH-independent forms result from autonomously hormone-producing adrenocortical tumours. In addition, special forms exist, such as subclinical (formerly “atypical”) CS, in which clinically typical signs are present, but established functional tests do not allow a definitive diagnosis.
This systematisation aims both to facilitate scientific communication and to improve clinical classification.

The next part of the panel focuses on the clinical symptomatology. Prof. Dr Nadja Sieber-Ruckstuhl emphasises that the majority of dogs with CS exhibit the classic signs of polyuria and polydipsia (PU/PD) as well as polyphagia. PU/PD is reported in over 80 % of cases, while increased food intake occurs in more than 50 %. She notes, however, that a certain proportion of patients do not show a clear manifestation of these symptoms. This may in part be attributed to increased awareness among dog owners and veterinarians of early, subtle clinical signs, resulting in affected animals being presented at an earlier stage of the disease. During the general clinical examination, notable findings include a distended but soft abdomen, thin and rather dry skin, abnormal fat distribution (e.g., central obesity), and muscle atrophy.

The participants asked about calcinosis cutis, how it is related to CS, and how it can be treated. PD Dr Florian Zeugswetter explains that it involves calcium deposits in the skin, which predominantly occur in the neck and back regions, but can also appear in the inguinal area or on the extremities. Its occurrence is described almost exclusively in association with glucocorticoid exposure, making calcinosis cutis nearly pathognomonic for CS. Certain breeds, such as Staffordshire Bull Terriers, Pitbull Terriers, and Rottweilers, show a particular predisposition. Clinically, these skin changes are often striking and may vary in severity. Prof. Dr Wolfgang Bäumer notes that the best therapeutic approach is consistent management of Cushing’s syndrome. Supportive measures, such as keratolytic shampoos or DMSO solutions, are discussed, although the evidence supporting their use is limited.

When asked about the prevalence of systemic hypertension in dogs with CS, PD Dr Astrid Wehner emphasises that approximately 80 % of CS patients are affected. Close monitoring is recommended for a systolic blood pressure of 160 mmHg or higher, while values above 180 mmHg carry a high risk of target organ damage, particularly at the renal and cardiovascular level.
Therefore, blood pressure measurement should be performed in all patients with CS.

PD Dr Astrid Wehner also provides a brief digression on proteinuria. Almost every second dog with CS exhibits proteinuria, with the urine protein-to-creatinine ratio (U-P/C) typically ranging from 1 to 3. However, more severe proteinuria with considerably higher U-P/C ratios is also possible.
The exact cause is unclear. In some patients, concomitant systemic hypertension is certainly contributory. PD Dr Wehner points out that study data demonstrate both glomerular sclerosis and tubular lesions. Nevertheless, most patients do not develop azotaemia despite these changes, and proteinuria does not appear to have prognostic significance. It often regresses under successful therapy, although not in all cases. PD Dr Wehner agrees with PD Dr Zeugswetter and Prof. Dr Sieber-Ruckstuhl that CS-associated proteinuria in dogs does not require separate treatment.

Cats can also develop Cushing’s syndrome, although it is significantly less common than in dogs. Dr Astrid Wehner addresses the differences compared with dogs, explaining that feline CS is frequently associated with diabetes mellitus. While this can also occur in dogs, it is not seen to the same extent: up to 80 % of cats with CS are diabetic.
Clinically, polyuria and polydipsia associated with often poorly controlled diabetes mellitus predominate. However, in contrast to dogs, these symptoms are considerably less pronounced in cats without diabetes mellitus. As in dogs, increased food intake is a typical clinical feature of CS. Affected cats lose weight, accompanied by marked muscle wasting, which is also a common finding in dogs.
Cats, like dogs, often present with a characteristic, pendulous, distended abdomen. The skin is thin, dry, and scaly, as is the case in dogs with CS, so the abdominal veins are particularly visible in both species. In cats, this effect is so pronounced that it leads to marked skin fragility. Consequently, poorly healing wounds are common, and even relatively minor mechanical stress can lead to extensive skin tears. The course of the disease in cats is usually insidious, which complicates early detection. Dr Pieter Nelissen notes that adrenal tumours are somewhat less common in cats than in dogs but still represent an important differential diagnosis. Adrenal cortical tumours in cats may produce cortisol as well as aldosterone or sex hormones, either concomitantly or instead of cortisol. Symptoms can be very similar, but diagnosis is more challenging. Prof. Dr Nadja Sieber-Ruckstuhl explains that altered sexual behaviour, such as sudden urine marking in neutered male cats or signs of oestrus in female cats, can sometimes provide a clue. During the general examination, in suspected cases, castrated male cats should be checked for penile spines, which are normally present only in intact animals.

The discussion then briefly addresses iatrogenic Cushing’s syndrome. It occurs relatively frequently in dogs and less often in cats. The question arises as to the dose and type of administered glucocorticoids at which it can be expected. Prof.

Dr Nadja Sieber-Ruckstuhl emphasises that this cannot be answered universally. Iatrogenic CS can be triggered by very low doses of glucocorticoids, particularly when administered over a prolonged period. There is a high degree of individual sensitivity, with large dogs often being particularly susceptible. The test of choice in cases where iatrogenic CS needs to be distinguished from naturally occurring CS is the ACTH stimulation test. In iatrogenic CS, it yields a result that would typically be expected for hypoadrenocorticism (no stimulation or borderline stimulation).

Another central topic is the diagnosis of CS. The discussion begins with the challenge posed by prior glucocorticoid treatment. Prof. Dr Nadja Sieber-Ruckstuhl explains that there are no validated guidelines in the literature regarding the optimal interval between glucocorticoid administration and a functional test. This interval depends on the specific preparation, dose, duration of administration, and individual sensitivity. In some patients, normal stimulation can be observed one week after withdrawal of exogenous glucocorticoids, while in others it may take months before there is no residual effect. As a general guideline, 6–8 weeks are often suggested. Prof. Dr Wolfgang Bäumer adds that numerous medications can influence cortisol levels: for example, butorphanol increases cortisol concentrations, whereas substances such as trazodone, lokivetmab, and bedinvetmab can reduce them—particularly by lowering stress and pain. This necessitates especially careful interpretation of test results.

The “ALIVE” group of the ESVE explicitly advises against the use of hormone tests for in-house diagnostics.

PD Dr Florian Zeugswetter agrees with the other experts that a single basal cortisol measurement is unsuitable for diagnostic purposes. In dogs with CS, cortisol overexposure typically results from an increased frequency of secretory peaks. A randomly obtained blood sample may therefore coincide with either a peak or a trough of cortisol secretion. Consequently, it is not possible to reliably distinguish affected from unaffected patients, regardless of whether the measured value is high or low.

The urine cortisol-to-creatinine ratio (UCC) can provide an initial orientation but should always be supplemented with functional tests. Prof. Dr Nadja Sieber-Ruckstuhl recommends analysing at least three individual samples, as pooled urine samples may distort the results. Urine should be collected at home by the owner. Following a veterinary visit, at least two days should elapse before starting the collection, as stress induced by the visit could result in false positive results.

PD Dr Florian Zeugswetter provides the participants with a more detailed discussion of the low-dose dexamethasone suppression test (LDDST), which is generally regarded as the test of choice for confirming the diagnosis of CS. However, the LDDST can be influenced by situations that increase cortisol secretion, such as emotional or disease-related stress. A positive result therefore confirms CS only in the context of compatible clinical signs and the exclusion of other diseases.
Following dexamethasone administration, physiological feedback suppresses endogenous cortisol production. A reduction of serum cortisol concentration below a defined cut-off is expected. In most patients with Cushing’s syndrome, this suppression is absent. Interpretation of the test is primarily based on the 8-hour value. For a definitive assessment, reduced suppression should also be evident in the intermediate time point (typically at 4 hours). Classically, the test is considered negative (i.e. CS is not present) if the 8-hour value is below the established cut-off, regardless of the intermediate value obtained at 3–4 hours.
However, a negative result is not necessarily conclusive; therefore, in cases of persistent clinical suspicion, repeat testing or the use of alternative diagnostic methods may be required.In cats, the LDDST is also considered the method of choice, although the dexamethasone dose must be adjusted to 0.1 mg/kg—ten times higher than in dogs.

Further questions from the audience concern the practical execution of the LDDST. One topic is the concentration of dexamethasone preparations. Some confusion arises from certain literature sources discussing the conversion of effective concentrations. Prof. Dr Wolfgang Bäumer explicitly refers to the concentration stated on the preparation itself. In German-speaking countries, this is always provided (“corresponds to x mg dexamethasone”). Additionally, participants asked how dexamethasone can be practically diluted for very small patients. PD Dr Florian Zeugswetter provides guidance: adding 1 ml of a 2 % dexamethasone preparation (2 mg/ml) to 9 ml of 0.9 % NaCl (mixed well) results in a final concentration of 0.2 mg/ml, which allows for easier dosing. For a dexamethasone concentration of 4 mg/ml, 0.5 ml of dexamethasone is added to 9.5 ml of 0.9 % NaCl to achieve the same final concentration of 0.2 mg/ml.

With regard to therapy, medical treatment with trilostane plays a central role. This drug inhibits cortisol synthesis through reversible enzyme blockade. Prof. Dr Wolfgang Bäumer notes that, despite its reversibility, irreversible adrenal cortical necrosis may occur in rare cases, leading to permanent hypoadrenocorticism. Concerning dosage, twice-daily administration of lower amounts is preferable to a single high daily dose. This is particularly beneficial in large-breed dogs, where it significantly reduces the risk of adverse effects. PD Dr Astrid Wehner advises caution in patients with chronic kidney disease. Reducing cortisol can lower the glomerular filtration rate and may consequently worsen the course of renal disease. Dr Pieter Nelissen adds information on surgical options: in cases of adrenal tumours, adrenalectomy is the treatment of choice, as approximately 50 % of these tumours are carcinomas. The complication rate of such surgery has been markedly reduced in recent years due to advances in surgical techniques and anaesthesia. Even when vascular invasion is present, surgical removal may still be possible. If a patient is already receiving trilostane, the medication should be discontinued 24–48 hours prior to surgery. The remaining contralateral adrenal gland is typically atrophied and requires time to regain function.
Postoperatively, a low dose of corticosteroids should therefore be administered and tapered over 4–6 weeks.

Monitoring was also discussed in detail. PD Dr Florian Zeugswetter favours pre-pill cortisol measurement as a cost-effective option, provided the patient’s clinical condition is stable and there is no suspicion of trilostane overdose. Blood sampling is carried out immediately before the next scheduled dose of trilostane. Prof. Dr Sieber-Ruckstuhl recommends double sampling at a one-hour interval to account for the effects of random peaks and stress responses. In this approach, one cortisol measurement is taken at the time when the trilostane dose would normally be administered, and a second measurement one hour later. The trilostane is only given after the second blood draw on that day. This procedure allows stress-induced high or incidentally low cortisol concentrations to be “balanced out”, potentially leading to a more accurate assessment of the patient. PD Dr Wehner reminds us that reduced appetite or decreased vitality may be early warning signs of trilostane overdose. The ACTH stimulation test offers the highest level of safety when assessing potential overdosing and should always be used when the patient shows clinical abnormalities. She also emphasises that the risk of therapy-induced hypoadrenocorticism increases with treatment duration. Close, lifelong monitoring using ACTH stimulation or pre-pill cortisol measurements are therefore indispensable.

Dr. Jennifer von Luckner

Expert Panel on Cushing’s Syndrome

Sex Determination in Snakes

Laboklin | Bad Kissingen | NAH — Mon, 17 Nov 2025 11:27:37 +0000

The keeping of reptiles in captivity is often undertaken with the aim of breeding the species in question. A fundamental prerequisite for successful breeding is knowledge of the sex of the animals.
Additionally, this information is necessary because same-sex individuals of many species can exhibit territorial behaviour, particularly upon reaching sexual maturity, which in the worst cases may result in aggressive encounters.

Although many reptiles, including numerous snake species, display clear sexual dimorphism, this is rarely apparent in juvenile animals, as it generally only develops over time. In many species, sexual dimorphism becomes fully expressed only upon reaching sexual maturity (Fig. 1). A prominent example is the anacondas (genus Eunectes), in which adult females grow many times larger than males. Another example is Wagler’s pit viper (Tropidolaemus wagleri), in which, in addition to sexual dimorphism, there is also sexual dichromatism—that is, a sex-specific difference in colouration and patterning.

While sex determination in adult individuals of many species is relatively straightforward, it becomes challenging in subadult or juvenile animals.
Correctly identifying the sex of hatchlings is particularly important, as these animals are typically transferred to new keepers at this early stage.

There are a number of manual methods for sex determination, each of which often has its own drawbacks.

1. Popping

The so-called “popping” technique involves manually everting the hemipenes of male snakes from the hemipenal pockets (Fig. 2). This method has the drawback that it is often applicable only to very young snakes, as the hemipenes of older individuals can no longer be everted. There is also a considerable risk of injury to the spinal region due to tail bending and the application of pressure immediately distal to the cloaca. Furthermore, there is always the risk of misidentification, as males may be incorrectly classified as females if eversion of the hemipenes is unsuccessful.

2. Probing

Probing involves inserting a metal probe into the hemipenes or hemiclitoral pockets just distal to the cloaca. The depth of insertion is measured by the number of subcaudal scales the probe passes. The deeper hemipenal pockets of male snakes allow for greater probe insertion. The main drawback is that probing very small snakes is simply not feasible due to the risk of injury, such as perforating the hemiclitoris of females (Fig. 3). There is also always a risk of misidentifi-cation, which can occur in either direction.

3. Visual Inspection

Certain characteristics can indicate a snake’s sex without further manipulation. These include, for example, tail shape or visible sexual traits, such as hemipenal pockets on the dorsal scales of colubrids (Fig. 4). However, these methods require considerable experience, are highly unreliable, and should be applied with great caution.

Due to the numerous drawbacks of classical methods, we have established a molecular biological approach that allows reliable sex determination in many species. This method detects specific genes on the W chromosome of female snakes (Fig. 5). Suitable sample materials include shed skins, mucosal swabs, or EDTA blood. The advantages are clear: sex determination can be performed irrespective of age, and there is no risk of injury. Sample collection is very straightforward and therefore poses no difficulties for snake keepers.

We have already successfully applied our method to over 80 snake species and continue to expand our offerings. Genetic sex determination is currently available for vipers, pit vipers, and most colubrid species. All commonly kept species, such as corn snakes, king snakes, and hognose snakes, can be reliably sexed. For boas and pythons, we are currently developing a separate method, with the aim of providing a genetic sexing test for these groups in the future.

Conclusion

Sex determination in snakes, particularly in hatchlings, has long been a challenge. The genetic test now provides a safe and reliable alternative to traditional methods.

Gregor Geisler

Canine Hypothyroidism: Improved Diagnosis with a Focus on rT3 and LC-MS/MS

Laboklin | Bad Kissingen | NAH — Wed, 29 Oct 2025 10:32:05 +0000

Canine hypothyroidism is considered a classic endocrinopathy with characteristic clinical manifestations. Despite seemingly clear clinical symptoms, establishing an accurate diagnosis remains a significant challenge.
Numerous retrospective studies have shown that up to 70% of dogs treated with levothyroxine (L-thyroxine) do not actually have hypothyroidism. The substantial discrepancy between the reported diagnostic rate and the true prevalence (estimated at 0.07–0.23%) highlights the need for a more refined diagnostic approach.

Non-thyroidal illness (NTI), the effects of medications, and method-related misinterpretations further complicate the diagnostic process.
Indiscriminate initiation of levothyroxine therapy carries the risk of overlooking relevant underlying conditions and unnecessarily increasing the metabolic stress. In the presence of concurrent heart disease or untreated/unrecognised hypoadrenocorticism, this can lead to decompensation and may be potentially fatal.

In this diagnostic grey zone, novel approaches such as the measurement of reverse T3 (rT3) and the analysis of relevant parameters using liquid chromatography–tandem mass spectrometry (LC-MS/MS) provide valuable additional diagnostic options.

Basics of Thyroid Physiology and Diagnostics

Thyroid function is regulated by the complex interaction within the hypothalamic-pituitary-thyroid axis. TRH released from the hypothalamus stimulates TSH secretion in the pituitary gland, which in turn triggers the thyroid gland to synthesise and secrete thyroid hormones, primarily thyroxine (T4). In serum, more than 99% of T4 is protein-bound, with total T4 comprising both the protein-bound and free fractions. Only the free fraction (fT4) is taken up into cells, where it undergoes 5′-deiodination being metabolized to triiodothyronine (T3), the biologically active hormone at the cellular level.

Alternatively, fT4 can be converted into biologically inactive reverse T3 (rT3), which is thought to play a role in cellular regulation and in preventing excessive levels of active T3.

The Diagnostic Pitfall: NTI and Methodological Limitations

In a typical case, the diagnosis of canine hypothyroidism is based on the combination of compatible anamnesis, clinical signs, haematological and biochemical findings, together with a T4 concentration below the reference interval and a simultaneous increase in TSH.

However, this pattern is not present in all cases in which hypothyroidism is suspected.
Many diseases can secondarily suppress thyroid hormone concentrations without any functional and/or structural thyroid abnormality. This so-called euthyroid sick syndrome (ESS or NTIS) is characterised by low T4 and/or fT4 concentrations with normal TSH. Interpreting such findings is problematic without further diagnostic work-up.

Additional challenges arise from breed-specific lower iodothyronine concentrations (e.g. Greyhounds, Basenjis) and from the interference of binding proteins or autoantibodies (thyroglobulin-, T3-, T4-autoantobodies) with routinely used immunoassay kits. Moreover, various medications (e.g. glucocorticoids, phenobarbital, sulphonamides) can also influence thyroid parameters.

LC-MS/MS: A Potential New Reference Method

LC-MS/MS has been established as a highly precise analytical technique. Unlike immunoassays, LC-MS/ MS enables the direct and specific quantification of T4, T3 and rT3 without interference from autoantibodies or medications. This makes it particularly valuable in diagnostically challenging cases. For example, while immunoassays can yield falsely low or falsely high results in the presence of thyroglobulin autoantibodies, LC-MS/MS provides a reliable representation of the actual hormone concentration.

At Laboklin, a method for the measurement of T4, T3 and rT3 using LC-MS/MS has been established and validated for veterinary medicine as part of a doctoral thesis. This allows for highly specific diagnostics, particularly in unclear cases. It can also be a reliable option for therapy monitoring or in cases of suspected hypothyroidism despite T4 concentrations within the reference range.

When interpreting T3 and T4 values measured by LC-MS/MS the method-specific reference intervals must be taken into account, as they differ from those obtained using other techniques.

Reverse T3 (rT3): Differentiating NTI from Hypothyroidism

rT3 is primarily produced when there is an excess of T4 or when conversion to active T3 is downregulated. In hypothyroidism, only minimal amounts of T4 are available for conversion, resulting in reduced rT3 concentrations. In contrast, NTI typically leads to normal or elevated rT3 levels: sufficient T4 is available, but the physiological demand for T3 is simultaneously markedly reduced (Fig. 1).

Initial studies confirm the diagnostic value of this parameter:

rT3 < 50 pg/ml, in combination with a low T4 concentration, strongly suggests hypothyroidism.
rT3 > 109 pg/ml makes hypothyroidism highly unlikely, even when T4 levels are reduced (Fig. 2).

Indication

This parameter is particularly valuable when T4 or fT4 concentrations are low, but no elevated TSH concentration is present to confirm the suspicion of hypothyroidism. This situation may occur in 20–30% of dogs with hypothyroidism, but it more frequently indicates a non-thyroidal illness (NTI).

Previous Experience with the Parameter

An initial multicentre study on rT3 was presented at an international congress (ECVIM) in 2024.
The study demonstrated that healthy dogs, dogs with hypothyroidism, and those with low T4 concentrations secondary to a non-thyroidal illness (NTI) could be reliably distinguished. A cut-off of 50 pg/ml was identified as highly specific for the presence of hypothyroidism, whereas concentrations above 109 pg/ml were incompatible with hypothyroidism. Values between these thresholds represented a grey zone. To establish a reference interval for rT3, Laboklin conducted a study in a larger population of clinically healthy, euthyroid dogs. This study determined a reference interval of 109–533 pg/ml.

In addition to the conducted studies, highly valuable field data have now become available.

Between March 2024 and June 2025, the rT3 parameter was requested 3,052 times at Laboklin, of which 1,887 requests were for rT3 alone and 1,165 were performed as part of a profile or as an add-on to initially requested thyroid parameters.

Among the 491 cases with an rT3 concentration below 50 pg/ml, T4 was also measured in our laboratory in 289 cases. Of these, 92% of the dogs exhibited T4 concentrations below the reference range, confirming the close functional relationship between reverse triiodothyronine and thyroxine.

Only in 22 cases (7.6%) with an rT3 concentration below 50 pg/ml was the T4 concentration within the reference range. This phenomenon can primarily be attributed to the limitations of the immunoassays routinely used for T4 measurement (e.g., Immulite 2000; Siemens, Germany). Falsely elevated T4 results may arise due to the presence of autoantibodies or suboptimal sample quality (haemolytic or lipaemic samples). These interfering factors are well recognised and can complicate the interpretation of results in routine diagnostics.

In 570 dogs with simultaneously low T4 concentrations, rT3 levels were clearly within the normal range (> 109 pg/ml). Such a result does not support a diagnosis of hypothyroidism, but rather indicates a non-thyroidal illness (NTI). Of course, a single measurement of even highly specific laboratory parameters cannot definitively determine that these dogs did not actually suffer from hypothyroidism, but rather from a non-thyroidal illness (NTI). In all cases that we were able to review in personal discussions with the attending veterinarians, the assessment was, however, confirmed.

Previous studies and clinical experience suggest a major advance in canine hypothyroidism diagnostics. The parameter appears to fulfil its promise. It should be regarded as an additional tool in the “hypothyroidism” toolbox. rT3 is not intended as an initial screening parameter, but rather as an add-on to an existing thyroid profile. Accordingly, it should be interpreted in the context of clinical findings as well as other thyroid parameters (Fig. 3).

For further diagnostics, determination of thyroglobulin-, T3-, T4-autoantibodies is available through extended thyroid profiles. Another option is the measurement of T3 and T4 concentrations using liquid chromatography–tandem mass spectrometry (LC-MS/MS), which is not affected by interfering factors such as sample quality or autoantibodies, allowing for more specific and precise results.

Conclusion

The precise diagnosis of canine hypothyroidism requires more than the assessment of T4 and TSH alone. In particular, an rT3 measurement and LC-MS/MS-based analyses provide crucial information in cases of diagnostic uncertainty.

Dr. Jennifer von Luckner, Niklas Wiesner, Dr. Ruth Klein

Our Services Related to Hypothyroidism

T4, TSH, fT4

T3, fT3

rT3

Thyroid Profile (T4, fT4, T3, fT3, TSH, ATG, T4-AK, T3-AK)

Hypothyroidism/NTI Profile (T4, fT4, reverse T3, TSH)

Thyroid Monitoring (T4, TSH, Creatinine, SDMA, ALT, AP, Troponin I)

Thyroid Mass Spectrometry (T4, T3, rT3 by HPLC-MS/MS)

Equine Liver Diseases: Early Diagnosis – Correct Treatment

Laboklin | Bad Kissingen | NAH — Tue, 28 Oct 2025 12:10:48 +0000

Liver disease is a common problem in horses. Increased liver enzyme activities are often detected incidentally or may be identified in patients showing non-specific clinical signs. In an evaluation of 817 serum samples analysed at Laboklin in autumn 2023, nearly 20% of the horses showed mildly elevated γ-GT values ranging from 50 to 150 U/l (Reference: <44 U/l). In almost 7% of

the cases, increased serum bile acid levels above 12 μmol/l were also observed. To evaluate the underlying cause of these alterations, it is important to interpret the values correctly and, if necessary, initiate further diagnostic investigations.

Introduction

The liver plays a role in several metabolic processes, including the metabolism of proteins, carbohydrates, and fats; the production of coagulation factors and bile; as well as the synthesis and storage of vitamins and the excretion of metabolic waste products, toxins, and drugs. Due to its diverse roles, the liver is exposed to various noxious agents that can lead to hepatic damage.

Clinical Signs of Liver Disease

A large proportion of liver diseases are subclinical. This is due to the liver’s substantial capacity for cellular regeneration. Liver failure occurs only when the loss of hepatocyte function exceeds their regenerative capacity, which generally requires damage to around 80% of the organ. This highlights the importance of recognising and interpreting non-specific clinical signs at an early stage, such as lethargy, inappetence, icteric sclerae and mucous membranes, weight loss, reduced performance, or episodes of colic. Early identification of a mild hepatopathy is associated with a positive prognosis.

More severe signs include hepatic encephalopathy, hepatocutaneous syndrome, bleeding tendency, photosensitivity, and diarrhoea.

Diagnostics

The laboratory diagnostic evaluation of liver diseases in horses is primarily based on the interpretation of liver-specific enzyme activities and functional parameters in serum. Additional laboratory results provide valuable information on the extent of liver damage as well as on possible underlying systemic diseases. Often, further investigations such as sonography and liver biopsy are required to clarify the aetiology (Fig. 1).

Blood Tests – Enzymes

Blood tests often provide the first indications of liver disease through the detection of elevated liver enzyme activities. The parameters are distinguished according to their localisation within the liver (hepatocellular, biliary). They can also be classified based on whether they are liver-specific or ubiquitous.

1. Hepatocellular Enzymes

a. Glutamate dehydrogenase (GLDH)
GLDH is an enzyme specifically found in hepatocytes. It is rapidly released into the serum during acute, cellular liver damage.
Due to its short half-life (approximately 14 hours, with complete decline after 3–5 days), it is particularly useful for detecting acute hepatocellular damage and is considered the most sensitive marker.

b. Aspartate aminotransferase (AST)
AST is not liver-specific, as it is present not only in hepatocytes but also in muscle cells and erythrocytes. Isolated elevations should always be interpreted in the context of GLDH, creatine kinase (CK), and LDH.

c. Lactate dehydrogenase (LDH)
LDH is present in numerous tissues, including cardiac and skeletal muscle as well as erythrocytes. Because of this widespread distribution, its diagnostic value for the liver is meaningful only when interpreted alongside other enzymes.

2. Biliary Enzymes

a. γ-Glutamyltransferase (γ-GT)
γ-GT is a liver-specific enzyme with a half-life of 3–4 days, although in some cases it may remain elevated for several weeks. This enzyme is mainly produced in the bile duct epithelium. Increased serum activity occurs primarily in cholestasis and biliary diseases. While also present in the kidney and pancreas, it is mainly liver-specific. In sport horses, isolated γ-GT elevations (>50–150 U/l) can occur during intensive exercise.

b. Alkaline phosphatase (AP)
AP also shows increased activity in cholestatic processes but is less organ-specific, as it is present in bone, placenta, and intestine. In young animals, elevated AP due to bone growth should be considered physiological.

Proper interpretation of values is essential to guide further diagnostics or determine the optimal timing for re-testing. For γ-GT, in cases of mild elevation (Table 1), re-evaluation after 2–4 weeks, possibly including additional herd mates, is recommended to clarify a toxic or infectious aetiology and to assess disease progression.

Table 1: Classification of liver enzyme elevation by degree

Degree of Elevation
Mild	2–3 × upper cut-off
Moderate	4–5 × upper cut-off
High	10 × upper cut-off

Blood Tests – Liver Function

Changes in liver enzyme levels provide only limited information on disease severity, prognosis, or aetiology. Additional liver function parameters can help to better assess the extent of damage and prognosis. Bile acids constitute the primary parameter for assessment.

Bile Acids
Bile acids are produced in hepatocytes, continuously secreted into the duodenum, and 90–95% are reabsorbed. When cell function is impaired, reabsorption is reduced or absent, leading to accumulation and increased serum concentrations. Values above 25 μmol/l are regarded as pathological and indicate a poor prognosis in chronic cases. In acute cases, high values are of less prognostic concern, but require close surveillance. Bile acids are a highly sensitive marker for functional liver insufficiency, particularly in chronic diseases.
Bilirubin
Bilirubin is derived from degradation of haemoglobin, conjugated in the liver, and excreted via bile. Values above 75 μmol/l are associated with the characteristic yellow discoloration of the sclera and mucous membranes (icterus, jaundice). Differentiating between conjugated and unconjugated bilirubin in the blood allows the cause to be classified as pre-hepatic, intra-hepatic, or post-hepatic.
A conjugated fraction of more than 25% indicates a hepatocellular or hepatobiliar origin. In chronic conditions, however, serum bilirubin concentrations may remain within the normal range.
Ammonia
Elevated blood ammonia levels indicate advanced liver insufficiency and can lead to hepatic encephalopathy. Measurement is challenging due to its low stability (maximum 30 minutes).

Imaging / Biopsy

Ultrasonography of the liver is a useful supplementary diagnostic tool, even if only a portion of the organ is accessible for imaging due to anatomical reasons. Although many changes are diffuse, ultrasonography can still provide valuable information. The absence of pathological findings does not rule out liver disease. Liver biopsies are indicated when clinical signs and laboratory values do not allow a definitive diagnosis. Samples can be submitted for histology, bacteriology, and pathogen detection via PCR.

Aetiology

Intoxication

Intoxications are among the most common causes of hepatopathies. They can arise from, for example, mycotoxins or moulds in roughage, microcystins from algae-contaminated water, or excessive iron intake.

Particular attention should be paid to poisonous plants in pastures and hay. Although horses usually avoid them, ingestion can occur under certain conditions (e.g. in young animals, during feed shortages, in the presence of exotic plants, or when plant parts are fragmented).

Species of Senecio, such as ragwort, can lead to altered liver enzyme activities even in the early stages of intoxication, often without clinical symptoms. The toxic agents are pyrrolizidine alkaloids (PAs), which can cause irreversible liver fibrosis with chronic exposure.

LC-MS analysis of urine allows detection of senecionine/senecionine-N-oxide and indicates toxin exposure in the preceding hours to days. Additionally, roughage analysis (e.g., through agricultural testing facilities) is recommended.

Infections

Viruses

Viral hepatitis in horses is increasingly well studied. Of particular relevance are equine hepacivirus (EqHV) and equine parvovirus-hepatitis virus (EqPV-H).

EqPV-H is associated with Theiler’s disease – an acute hepatitis with fulminant liver necrosis and usually fatal outcome. Transmission is likely via blood products (e.g., tetanus antitoxin, stem cell products, equine plasma), and possibly via vectors. The virus is widespread worldwide, with seroprevalences in healthy horse populations (e.g., Germany, Austria) ranging between 15% and 34.7%, though only about 2% develop clinical disease. EqPV-H should be considered in the differential diagnosis when relevant symptoms are present.

EqHV, first described in 2012, can cause acute or chronic persistent infections. Symptoms range from weight loss, anorexia and jaundice to neurological abnormalities.

Both viruses are detectable by PCR in blood or liver tissue during the acute stage. Histopathological examination of liver biopsies can additionally help to assess the severity and prognosis of liver damage.

Bacteria

Bacterial liver disease is rare and usually secondary. When it occurs, it is often severe. It typically involves ascending bacterial infections, e.g., with Streptococcus equi or Staphylococcus aureus. In foals, liver abscesses can be caused by Rhodococcus equi and young animals may develop Tyzzer’s disease due to Clostridium piliforme. Clinically, bacterial hepatitis usually presents with jaundice, fever and colic. Pathogen detection can be performed on liver biopsy samples, which can be evaluated microbiologically and histologically. PCR-based detection is also an option.

Parasites

Parasitic liver damage occurs due to migrating stages of, for example, Strongylus spp. and Parascaris equorum. Liver fluke (Fasciola hepatica) is rare in horses but may occur in mixed pastures with ruminants or in wetland areas where water snails are present. Lesions can affect both liver parenchyma and bile ducts. In suspected cases, faecal samples can provide proof of infection; for some parasites (Fasciola hepatica, small strongyles/ small redworm), serology is more sensitive.

Conclusion

Hepatopathies are often detected late due to non-specific symptoms and subclinical cases. Diagnosis is based on the determination of liver enzyme activities and functional parameters, supported by diagnostic imaging techniques and, if necessary, liver biopsy. Toxic and infectious causes are most common, while environmental and dietary factors should also be considered when investigating the aetiology. Treatment efficacy is monitored through regular assessment of liver enzyme activities.
Recovery, however, can take weeks to months. As a preventive measure, depending on the aetiology, feed and pasture hygiene as well as evidence-based parasite control management can be helpful.

Dominika Wrobel-Stratmann, Dr. Svenja Möller,
Dr. Michaela Gentil

Our Services in Equine Liver Diagnostics

Profile	Parameters	Sample Material
Liver 1	AST, GLDH, γ-GT, bile acids	Serum
Liver 2	GLDH, AST, AP, γ-GT, total bilirubin, cholesterol, urea, bile acids, protein, albumin, globulins, albumin/globulin ratio, glucose, Na, K, Cl	Serum and NaFB
Hepatotropic Viruses	PCR: equine parvovirus, equine hepacivirus	Serum, EDTA blood, liver tissue
Parasite Profile	Flotation, SAFC, modified McMaster method	Faeces
Coagulation	PT, PTT, thrombin time, fibrinogen	Citrate plasma
Bilirubin	Total and direct	Serum, EDTA plasma, heparin plasma
Single Analyses
Bile Acids		Serum
Serum Protein Electrophoresis	Albumin, α-globulins, β-globulins, γ-globulins, total protein	Serum
Liver Fluke (Antibody Detection)		Serum
Small Redworm Test (Antibody Detection)	Detects infection levels of all small redworm stages	Serum
Meadow Saffron	Colchicine	Urine
Ragwort	Senecionine, senecionine-N-oxide	Urine
Bacteriology	Aerobes, anaerobes	Swab with medium, tissue (native)
Histopathology		Tissue (fixed)

Spontaneous Tumours in Guinea Pigs (Cavia porcellus): Retrospective Evaluation of Routine Submissions

Laboklin | Bad Kissingen | NAH — Tue, 30 Sep 2025 06:47:56 +0000

According to a 2020 survey conducted by the Pet Supplies Industry Association, five million small pets live in 5% of all households in Germany. An important representative of this group of animals is the guinea pig (Cavia porcellus). Originally native to South America, guinea pigs were brought to Europe by Spanish sailors as early as the 16th century.
In their native regions, they are kept as livestock for meat production. In Central Europe, however, domestic guinea pigs are primarily kept as pets.
When kept as companion animals, guinea pigs often reach a higher age than in the wild. This inevitably leads to diseases that primarily affect adult and older animals, such as tumours.

Only a few review articles on spontaneous tumours in guinea pigs have been published to date (Dobromylskyj et al., 2023). In recent years, pet owners have become increasingly willing to have their animals examined and treated in the event of illness. To gain an overview of the types of tumours occurring in guinea pigs, tumour submissions received by Laboklin between 2013 and 2020 were evaluated. The inclusion criteria were the specification of the tumour location and samples for which a clear diagnosis could be made. During the study period, these criteria were met by 1,017 tumours.

The following analysis focuses on the anatomical locations of these tumours, the most frequently diagnosed tumour types, whether benign or malignant neoplasms predominated, and the unusual tumours that were identified in this population.

Tumour Localisation

The submitted tumours originated from a wide range of anatomical locations, with tumours of the skin and subcutaneous tissue being the most frequently submitted. These were followed by tumours of the mammary gland tissue, uterus, and lymphatic tissue. Thyroid tumours were also represented. Neoplastic changes in other organs were submitted much less frequently (Fig. 1). Since tumours of the skin and subcutaneous tissue are easily noticed by owners during handling and grooming of the animals, this is presumably one of the main reasons why neoplasms at these sites were most frequently submitted. In contrast, pathological processes affecting internal organs are not necessarily detected by the owner or may require more complex surgical interventions.

Tumour Diagnoses

Lipoma was the most frequently diagnosed tumour in guinea pigs, followed by hair follicle tumours. Numerous other tumour types were also identified (Fig. 2). Given that the majority of samples originated from the skin and subcutaneous tissue, it is not surprising that tumours of adipose tissue and hair follicles were the most commonly diagnosed.

Frequency of Benign and Malignant Tumours

To provide a clearer overview of the ratio of benign to malignant tumours, this is illustrated schematically for the most frequently submitted tumour types (Fig. 3).

The most frequently occurring mesenchymal and epithelial tumours of the skin and subcutaneous tissue were further analysed to provide a clearer overview and to assess whether benign or malignant neoplasms predominated.

Mesenchymal Tumours of the Skin and Subcutaneous Tissue

In guinea pigs, mesenchymal tumours predominated in the skin and subcutaneous tissue. A total of 508 mesenchymal tumours were diagnosed, of which 365 were benign and 143 were classified as malignant. The tumours included 325 lipomas, 13 fibromas, 13 fibrolipomas, and 6 haemangiomas. An additional 8 benign tumours were identified. Furthermore, 80 sarcomas were submitted, although a clear determination of the cell of origin was not possible. In addition, 29 fibrosarcomas, 24 liposarcomas (Fig. 4), and 10 other malignant mesenchymal neoplasms were diagnosed.

Epithelial Tumours of the Skin and Subcutaneous Tissue

A total of 157 epithelial tumours were submitted, of which 142 were benign and 15 were malignant. The benign tumours comprised 124 trichofolliculomas (Fig. 5), 5 trichoepitheliomas, 3 pilomatrixomas, 3 adenomas, and 7 other benign neoplasms. The malignant tumours included 5 adenocarcinomas, 5 unclassified carcinomas, 3 squamous cell carcinomas, and 2 sebaceous gland carcinomas.

The other tumours of the skin and subcutaneous tissue included 11 cutaneous lymphomas, 3 melanomas, 1 fibropapilloma, and 1 carcinosarcoma.

Lymphomas

Lymphomas also occur regularly in guinea pigs. In addition to lymphoma, a form of leukaemia has been described, particularly affecting young adult animals (under 3 years of age). These animals usually die within a few weeks.

The 46 lymphomas included in this study were predominantly located in the lymph nodes (n = 31), but also in the skin (n = 11), internal organs (n = 3), and the eye (n = 1).

A special form of cutaneous lymphoma is the cutaneous epitheliotropic lymphoma (syn. mycosis fungoides). This is a progressive tumour disease, characterised by infiltration of tumour T lymphocytes (memory T cells) into the epidermis and adnexa (Moore & Olivry, 1994). The aetiology of this disease is not yet fully understood. This form of lymphoma also occurs in guinea pigs and is often not initially recognised as a tumour. Clinically, erythema, alopecia, and scaling may be observed, often leading to an initial suspicion of a skin disease. Nodular proliferations may only develop at later stages of the disease (Fig. 6).

Mammary Tumours

In contrast to other animal species, mammary tumours are also regularly observed in male guinea pigs (Table 1) (Schöniger et al., 2025). During the study period, 157 tumours were submitted, of which 75 originated from female animals and 58 from male animals; the sex of 24 animals was unknown. A total of 78 adenomas, 7 fibroadenomas, 71 adenocarcinomas, and 1 undifferentiated carcinoma were diagnosed.

Table 1: Distribution of mammary tumours by sex

Diagnosis	Number	F	FS	M	MS	U
Total	157	74	1	44	14	24
Benign	85	47	–	17	7	14
Malignant	72	27	1	27	7	10

Legend: F: female, FS: female spayed, M: male, MS: male castrated, U: sex unknown.

Uterine Tumours

In contrast to rabbits, guinea pigs exhibit a wide range of uterine changes, which can be non-neoplastic or proliferative. Simple benign or malignant tumours may occur, and mixed tumours can also be diagnosed (Laik-Schandelmaier et al., 2017).

Between 2013 and 2020, 60 tumours from the uterine region were submitted, of which 37 were benign and 23 malignant. The tumours were classified as 28 epithelial, 27 mesenchymal, and 5 mixed tumours. Among the epithelial neoplasms, 19 adenomas were observed compared with 9 adenocarcinomas. Among the mesenchymal tumours, 17 leiomyomas, 8 leiomyosarcomas, and 2 undifferentiated sarcomas were identified. Of the mixed tumours, only one was benign, whereas four were malignant.

Thyroid Tumours

In contrast to other small mammals, guinea pigs frequently develop thyroid tumours. During the study period, 15 adenomas and 14 carcinomas were diagnosed.

Conclusion

In the present study of spontaneous tumours in guinea pigs, benign neoplasms of the skin and subcutaneous tissue predominated. Lipomas were by far the most common tumours, followed by trichofolliculomas. Cutaneous epitheliotropic lymphomas can be clinically difficult to distinguish from inflammatory skin conditions.
Mammary tumours occurred in both female and male guinea pigs. In this study, castrated females and males were less frequently affected than intact animals.
Histopathology is an important tool for the prognostic assessment of tumours, as neoplasms of the mammary gland, uterus, and thyroid can be either benign or malignant.
This study demonstrates that a tumour diagnosis in guinea pigs does not necessarily constitute a death sentence. In many cases, the underlying lesion is benign, and timely veterinary intervention with removal of the mass allows the animal to continue a normal, healthy life.

Dr Claudia Schandelmaier

Services offered
– Histopathology
– Cytology

Further Literature

Dobromylskyj MJ, Hederer R, Smith KC. Lumpy, bumpy guinea pigs: a retrospective study of 619 biopsy samples of externally palpable masses submitted from pet guinea pigs for histopathology. J Comp Pathol. 2023 May;203:13-18. doi: 10.1016/j.jcpa.2023.04.001.

Laik-Schandelmaier C, Klopfleisch R, Schöniger S, Weiffenbach G, Staudacher M, Aupperle H. Spontaneously Arising Tumours and Tumour-like Lesions of the Cervix and Uterus in 83 Pet Guinea Pigs (Cavia porcellus). J Comp Pathol. 2017 May;156(4):339-351. doi: 10.1016/j. jcpa.2017.03.002.

Moore PF, Olivry T. Cutaneous lymphomas in companion animals. Clin Dermatol. 1994 Oct-Dec;12(4):499-505. doi: 10.1016/0738-081x(94)90216-x.

Schöniger S, Schandelmaier C, Aupperle-Lellbach H, Koppel C, Zhang Q, Schildhaus HU. Neoplastic and Non-Neoplastic Proliferative

Mammary Gland Lesions in Female and Male Guinea Pigs: Histological and Immunohistochemical Characterization. Animals (Basel). 2025 May 28;15(11):1573. doi: 10.3390/ani15111573.

Spontaneous Tumours in Guinea Pigs (Cavia porcellus): Retrospective Evaluation of Routine Submissions

LABOKLIN Europe

New Diagnostic Tests for Fish and Reptiles

Columnaris disease in koi and aquarium fish

Emydomyces testavorans – a cutaneous fungus in turtles

Further Reading

Untergasser D. Krankheiten der Zierfische. Ettlingen (DE): Dähne Verlag; 2024. Buller NB. Bacteria and fungi from fish and other aquatic animals: a practical identification manual. 2nd ed. Oxfordshire (UK): CABI; 2014.

Simmons A, Brunner T, Ospina E, Wong A, Keller K, Adamovicz L. Emydomyces testavorans DNA is detected from shell swabs of companion chelonians. J Exot Pet Med. 2024;50:49–53. doi:10.1053/j.jepm.2024.05.005.

Liszka NC, Adamovicz L, Moorhead KA, Daleo MJ, Grochowski K, Allender MC. Evaluating the Efficacy of Disinfectant Methods against Emydomyces testavorans, a Fungus Associated with Shell Disease in Freshwater Aquatic Turtles. J Wildl Dis. 2025 Jan 1;61(1):234-240. doi: 10.7589/JWD-D-24-00094.

Woodburn DB, Miller AN, Allender MC, Maddox CW, Terio KA. Emydomyces testavorans, a New Genus and Species of Onygenalean Fungus Isolated from Shell Lesions of Freshwater Aquatic Turtles. J Clin Microbiol. 2019 Jan 30;57(2):e00628-18. doi: 10.1128/JCM.00628-18

Woodburn DB, Kinsel MJ, Poll CP, Langan JN, Haman K, Gamble KC, Maddox C, Jeon AB, Wellehan JFX, Ossiboff RJ, Allender MC, Terio KA. Shell Lesions Associated With Emydomyces testavorans Infection in Freshwater Aquatic Turtles. Vet Pathol. 2021 May;58(3):578-586. doi: 10.1177/0300985820985217

Laboratory Diagnostic Evaluation of Body Cavity Effusions

Sample Preparation

Effusion Analysis – Macroscopic Findings

Basic Parameters

Specialised Investigations

Cytology

Conclusion

Further Reading:

Alleman AR. Abdominal, thoracic, and pericardial effusions. Vet Clin North Am Small Anim Pract. 2003 Jan;33(1):89-118. doi: 10.1016/s0195-5616(02)00057-8.

Aupperle-Lellbach H, Schandelmaier C, Jäger K, Appenzeller M, Loesenbeck G, Törner K. Aktuelles zur Tumordiagnostik in der Veterinärpathologie Teil 4: Tumorzytologie. Kleintiermedizin. 2025;1:52–67.

Boes KM. Body cavity fluids. In: Raskin RE, Meyer D, Boes KM, editors. Canine and Feline Cytopathology: A Color Atlas and Interpretation Guide. 4th ed. St. Louis (MO): Elsevier; 2023. p. 242–286.

Kaiser LK, Weiler K. Labordiagnostische Aufarbeitung von Körperhöhlenergüssen bei Hunden und Katzen. Tierärztl Prax Ausg K Kleintiere Heimtiere. 2025;53:220–235.

Parra MD, Papasouliotis K, Cerón JJ. Concentrations of C-reactive protein in effusions in dogs. Vet Rec. 2006 Jun 3;158(22):753-7. doi: 10.1136/ vr.158.22.753.

Probo M, Valenti V, Venco L, Paltrinieri S, Lavergne E, Trumel C, Bertazzolo W. Pleural lymphocyte-rich transudates in cats. J Feline Med Surg. 2018 Aug;20(8):767-771. doi: 10.1177/1098612X17731045.

von Hohnhorst IM, Weiler K. Ergussanalyse – Fokus auf die zytologische Auswertung. Tierärztl Prax Ausg K Kleintiere Heimtiere. 2025;53:236–247.

Zoia A, Petini M, Righetti D, Caldin M, Drigo M. Discriminating transudates and exudates in dogs with pleural effusion: diagnostic utility of simplified Light’s criteria compared with traditional veterinary classification. Vet Rec. 2020 Jul;187(1):e5. doi: 10.1136/vr.105650.

Acute-Phase Proteins in Dogs and Cats – Current Insights and Clinical Relevance

Dogs – CRP as the Gold Standard

Acute-Phase Index (API) – a Combined Marker

Cats – Focus on SAA and AGP

Serum Amyloid A (SAA)

Alpha-1-acid Glycoprotein (AGP)

Haptoglobin (Hp)

Negative Acute-Phase Proteins

Acute-Phase Proteins in FIP

Further Reading:

Malin K, Witkowska-Piłaszewicz O. C-Reactive Protein as a Diagnostic Marker in Dogs: A Review. Animals (Basel). 2022 Oct 21;12(20):2888. doi: 10.3390/ani12202888.

Viitanen SJ, Lappalainen AK, Christensen MB, Sankari S, Rajamäki MM. The Utility of Acute-Phase Proteins in the Assessment of Treatment Response in Dogs With Bacterial Pneumonia. J Vet Intern Med. 2017 Jan;31(1):124-133. doi: 10.1111/jvim.14631.

Waugh EM, Haining H, Harvie J, Ridyard AE, Eckersall PD. Validation of an automated immunoturbidimetric assay for feline serum amyloid A. BMC Vet Res. 2022 Sep 28;18(1):359. doi: 10.1186/s12917-022-03456-5.

Kurtz M, Pey PBM, Mortier J, Manassero M, Da Riz F, Canonne-Guibert M, Maurey C, Benchekroun G. Usefulness of serum amyloid A for the diagnosis of pyelonephritis in cats: A prospective evaluation. J Vet Intern Med. 2024 May-Jun;38(3):1542-1552. doi: 10.1111/jvim.17082.

Tršar L, Štrljič M, Svete AN, Koprivec S, Tozon N, Žel MK, Pavlin D. Evaluation of selected inflammatory markers in cats with feline infectious peritonitis before and after therapy. BMC Vet Res. 2025 May 9;21(1):330. doi: 10.1186/s12917-025-04731-x.

Rossi G. Acute phase proteins in cats: Diagnostic and prognostic role, future directions, and analytical challenges. Vet Clin Pathol. 2023 Feb;52 Suppl 1:37-49. doi: 10.1111/vcp.13238.

Martínez-Subiela S, Ceron JJ. Evaluation of acute phase protein indexes in dogs with leishmaniasis at diagnosis, during and after short-term treatment. Vet Med – Czech, 2005, 50(1):39-46. doi: 10.17221/5595-VET-MED.

Paltrinieri S. The feline acute phase reaction. Vet J. 2008 Jul;177(1):26-35. doi: 10.1016/j.tvjl.2007.06.005.

Eckersall PD, Bell R. Acute phase proteins: Biomarkers of infection and inflammation in veterinary medicine. Vet J. 2010 Jul;185(1):23-7. doi: 10.1016/j.tvjl.2010.04.009.

Ceron JJ, Eckersall PD, Martýnez-Subiela S. Acute phase proteins in dogs and cats: current knowledge and future perspectives. Vet Clin Pathol. 2005 Jun;34(2):85-99. doi: 10.1111/j.1939-165x.2005.tb00019.x.

Shih AW, McFarlane A, Verhovsek M. Haptoglobin testing in hemolysis: measurement and interpretation. Am J Hematol. 2014 Apr;89(4):443-7. doi: 10.1002/ajh.23623.

Hazuchova K, Held S, Neiger R. Usefulness of acute phase proteins in differentiating between feline infectious peritonitis and other diseases in cats with body cavity effusions. J Feline Med Surg. 2017 Aug;19(8):809-816. doi: 10.1177/1098612X16658925.

Tasker S, Addie DD, Egberink H, Hofmann-Lehmann R, Hosie MJ, Truyen U, Belák S, Boucraut-Baralon C, Frymus T, Lloret A, Marsilio F, Pennisi MG, Thiry E, Möstl K, Hartmann K. Feline Infectious Peritonitis:

European Advisory Board on Cat Diseases Guidelines. Viruses. 2023 Aug 31;15(9):1847. doi: 10.3390/v15091847.

Equine Sarcoidosis

Introduction

Clinical Presentation

Pathogenesis

Diagnosis and Diﬀerential Diagnosis

Treatment and Prognosis

Further Reading

https://uploads.laboklin.com//lp1225

Allergen-specific Immunotherapy in Horses: Causes of Early Discontinuation and Strategies to Improve Outcomes

Survey-based Study at Laboklin

Reasons for ASIT Discontinuation

How Can ASIT Discontinuation Be Reduced and Treatment Success Optimised?

Conclusion

Further reading

Graner A, Mueller RS, Geisler J, Bogenstätter D, White SJ, Jonsdottir S, Marti E. Allergen immunotherapy using recombinant Culicoides allergens improves clinical signs of equine insect bite hypersensitivity. Front Allergy. 2024 Sep 30;5:1467245.

Herrmann I, Sanchez AJ. Efficacy and Safety of Subcutaneous Allergen-Specific Immuno-Therapy in Horses with Allergic Cutaneous and Respiratory Diseases-A Systematic Review. Vet Sci. 2023 Oct 10;10(10):613

Hunsinger B. Diagnostik und Spezifische Immuntherapie allergisch bedingter Erkrankungen. pferde spiegel 2003; 6(4): 10-14.

Marsella R, White S, Fadok VA, Wilson D, Mueller R, Outerbridge C, Rosenkrantz W. Equine allergic skin diseases: Clinical consensus guidelines of the World Association for Veterinary Dermatology. Vet Dermatol. 2023 Jun;34(3): 175-208.

Reinbacher E, Wagner R, Mueller E. Die Allergen-spezifische Immuntherapie (ASIT) bei Hunden mit atopischer Dermatitis – Was sind die Gründe für einen Behandlungsabbruch und wie kann der Behandlungserfolg optimiert werden? Kleintierpraxis 2025 May;70:236–246.

Stepnik CT, Outerbridge CA, White SD, Kass PH. Equine atopic skin disease and response to allergen-specific immunotherapy: a retrospective study at the University of California-Davis (1991-2008). Vet Dermatol. 2012 Feb;23(1):29-35, e7.

Expert Panel on Cushing’s Syndrome

The “ALIVE” group of the ESVE explicitly advises against the use of hormone tests for in-house diagnostics.

Sex Determination in Snakes

1. Popping

2. Probing

3. Visual Inspection

Conclusion

Further Reading

Pyron RA, Burbrink FT, Colli GR, de Oca AN, Vitt LJ, Kuczynski CA, Wiens JJ. The phylogeny of advanced snakes (Colubroidea), with discovery of a new subfamily and comparison of support methods for likelihood trees. Mol Phylogenet Evol. 2011 Feb;58(2):329-42. doi: 10.1016/j. ympev.2010.11.006.

Canine Hypothyroidism: Improved Diagnosis with a Focus on rT3 and LC-MS/MS

Untergasser D. Krankheiten der Zierfische. Ettlingen (DE): Dähne Verlag; 2024.
Buller NB. Bacteria and fungi from fish and other aquatic animals: a practical identification manual. 2nd ed. Oxfordshire (UK): CABI; 2014.