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

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.

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.

Laboklin’s expert panels continue to be very popular. This session focused on granulocytic anaplasmosis in dogs, cats, and horses. We have summarised the key insights and assessments from the experts for you. The discussion was lively, practice-oriented, and full of valuable advice from clinical practice, laboratory diagnostics, and research.

The expert panel included Prof. Dr. Reto Neiger, PhD, EBVS Specialist and Diplomate ECVIM-CA (Internal Medicine), Dipl. ACVIM (SAIM), Medical Director of IVC Evidensia DACH; Prof. Dr. Jessica-Maximilliane Cavallieri, EBVS Specialist and Diplomate ECEIM, Head of Internal Medicine at the Clinical Centre for Horses, Vetmed Uni Vienna; PD Dr. Barbara Willi, PhD, EBVS Specialist and Diplomate ECVIM-CA (Internal Medicine), Dipl. ACVIM, Lecturer and Senior Clinician at the Small Animal Clinic, Vetsuisse Faculty, University of Zurich, and Specialist in Internal Medicine and Infectious Diseases at Tierklinik Aarau West; Dr. Ingo Schäfer, M.Sc, Resident ECVCP in Laboratory Diagnostics at Laboklin, with a focus on vector-borne diseases; and Prof. Dr. Christina Strube, PhD, Director of the Institute for Parasitology at the University of Veterinary Medicine Hannover.

Clinical Signs and Observations

Reto Neiger provides an introductory overview of the clinical signs of anaplasmosis in dogs. He describes the clinical signs as largely nonspecific, with lethargy, anorexia, and fever being common, but lameness, gastrointestinal disturbances, coagulation disorders, and even pericardial effusions can also occur. He emphasises that lameness is often more accurately described as general reluctance to move.
Ingo Schäfer notes that cases of encephalitis have been reported in dogs, although these are rare, and he refers to individual cases in which the pathogen was detected in cerebrospinal fluid. Barbara Willi adds that in cats, the symptoms are similarly nonspecific, most commonly including lethargy, fever, anorexia, and reduced appetite.
In horses, Jessica Cavallieri reports that high fever, apathy, and icterus are the most prominent signs.

Ataxia and even epileptiform seizures can occur, and atypical courses involving rhabdomyolysis or dysphagia have also been described.

Typical Changes in Blood Tests

When discussing laboratory findings, Ingo Schäfer explains that thrombocytopenia is the most common haematological abnormality in dogs.
Other notable changes include anaemia, lymphocytosis, and increased globulins accompanied by hypoalbuminaemia.
Barbara Willi notes that in cats, thrombocytopenia is often less pronounced. As platelet counts may be measured inaccurately in cats due to aggregation, microscopic examination is essential to confirm thrombocytopenia.
Jessica Cavallieri describes that in horses, hyperbilirubinaemia is frequently observed, often accompanied by leukopenia and mild anaemia. Serum amyloid A (SAA) and fibrinogen levels are usually markedly elevated, while albumin is decreased.

Transmission and Prevalence

When asked about Anaplasma, Jessica Cavallieri explains that these are intracellular bacteria that depend on host cell components. Anaplasma (A.) phagocytophilum primarily infects neutrophil granulocytes, and to a lesser extent eosinophilic granulocytes, hence the term granulocytic anaplasmosis.
Christina Strube emphasises that transmission occurs via ticks of the genus Ixodes ricinus.
Although Anaplasma DNA has been detected in other tick species, this does not necessarily mean that they function as vectors. She notes that transmission typically occurs only 48 hours after a tick bite. While the disease shows a seasonal pattern with a spring peak, it should be considered a year-round concern.
Ingo Schäfer confirms that seroprevalence is high, around 20–30 % in central Europe for both dogs and horses, with regional variation. Reto Neiger reports that the clinical incidence of disease in dogs has not increased over the years. Jessica Cavallieri adds that, in horses, the risk of infection is widespread including higher altitudes, though the disease incidence remains relatively moderate.

Diagnostics

Barbara Willi cautions against overestimating the value of antibodies. Due to the high seroprevalence, they are not reliable for detecting an acute infection and should not be used as the sole basis for determining whether a clinically relevant and treatable granulocytic anaplasmosis is present. A single positive antibody titre does not justify therapy; diagnosis should instead be based on direct pathogen detection.
Reto Neiger emphasises the importance of PCR for diagnosis. In animals showing clinical symptoms, morulae should first be sought in a blood smear, followed by PCR confirmation. Barbara Willi explains that morulae are typical basophilic inclusions in granulocytes and can serve as evidence of infection. Blood smear examination for morulae offers a rapid, indicative diagnostic tool, though she agrees with Ingo Schäfer that identifying them requires practice. Moreover, morulae are present only within a limited time window after infection and can easily be missed.
Jessica Cavallieri confirms that these considerations also apply to horses, where a positive PCR is essential for diagnosis. Therapy based solely on suspicion from a positive antibody result is not appropriate. Ingo Schäfer adds that antibody testing may be unhelpful even if negative, as it may be too early for antibodies to have formed in acute cases; a negative titre therefore does not automatically rule out infection.
Asked whether paired serum samples showing a rising titre could be used diagnostically, Reto Neiger takes a critical view of this approach, noting that granulocytic anaplasmosis is an acute disease that must be treated during its symptomatic phase.
Decisions regarding therapy cannot rely on a titre increase detectable 2–4 weeks later.

Therapy and Prognosis

When asked about treatment recommendations, Reto Neiger mentions a doxycycline dosage of 5 mg/kg twice daily (BID) or 10 mg/kg once daily (SID). Unlike the previously common recommendation of a four-week course, current practice often limits therapy to two to three weeks. Barbara Willi confirms that in most cases, two to three weeks of treatment is sufficient, although evidence-based data are lacking. From an antimicrobial stewardship perspective, shorter treatment durations are desirable. A large systematic literature review of A. phagocytophilum infections in humans reported a mean treatment duration of 13 days. A treatment period shorter than two weeks is currently not recommended.
For cats, Ingo Schäfer reminds us that it is crucial to administer doxycycline with food or water, as tablets remaining in the oesophagus can cause severe inflammation and strictures.
Jessica Cavallieri explains that in horses, oxytetracycline or doxycycline is used depending on the clinical situation and tolerability. Monitoring therapy using PCR is not necessary, a point also confirmed by the other experts for dogs and cats. Treatment success is assessed primarily through improvement in clinical signs and the resolution of laboratory abnormalities.

All experts expressed an optimistic prognosis. Chronic infection does not appear to occur, although reinfections are possible. Infection with A. phagocytophilum induces antibodies but does not appear to confer lasting immunity.

Prophylaxis and Tick Protection

Christina Strube emphasises that veterinary-prescribed tick repellents provide the most reliable prevention. Caution is advised when using alternative products from pet shops, as some do not offer consistent protection. Regarding popular household remedies, such as lavender or rosemary extracts, she is similarly critical, noting that these do not achieve the necessary level of tick protection.
Instead, she recommends using products that are tailored to the individual animal’s lifestyle, following veterinary advice.
It is important that the products act quickly—ideally within the time frame before pathogen transmission occurs. Protection is also advisable during winter, as ticks are now active year-round due to milder temperatures. While many proven, effective antiparasitic products are available for dogs and cats, tick prophylaxis in horses is more challenging. Permethrin-based products require very frequent application to maintain consistent efficacy. Oral antiparasitics, which are commonly used in dogs and cats, show poor bioavailability in horses and are therefore unlikely to serve as a viable alternative in the future.

Dr Jennifer von Luckner

The Importance of Drinking Water

Adequate water intake is essential to ensure high forage consumption. For this reason, water provision is a key aspect of feed management.
How can I ensure that animals drink enough? And how can I verify whether water intake is sufficient? Can data analysis help to monitor and optimise water consumption?

Drinking water analyses are primarily conducted on farms that use well water, usually on a regular basis as part of quality assurance. Similarly, when inconsistencies arise in the feed ration, the drinking water is often analysed, e.g. to determine how the supply of macro- and trace elements should be adjusted if the water is rich in certain elements.

It is also advisable to include drinking water analysis in investigations when disease incidence is high. What constitutes good-quality drinking water? What role do biofilms play in disease development?

Do Our Cows Drink Enough?

Dairy cows have a particularly high water requirement. Their bodies consist of up to 80 % water, and their daily requirement—depending on age, milk yield, ambient temperature, and feed intake—can reach up to 170 litres/day.

Appuhamy et al. (2016) describe the key factors determining the water requirements of dairy cows as follows:

• DMI – dry matter intake (kg/day)
• Milk – milk yield (kg/day)
• DM % – dry matter content of the ration (%)
• CP % – protein content of the ration (%)
• BW – body weight (kg)
• TMP – ambient temperature (°C)
• Na and K – concentrations of sodium and potassium in the ration

Water serves as a transport medium in the cow’s body and is essential for metabolism, thermoregulation, digestion, and immune function.

If water quality is poor, feed intake decreases significantly. Adequate water intake is also essential for milk production.

The factors influencing water intake are diverse.
Well-planned barn design with a sufficient number of appropriately sized and correctly positioned drinking troughs allows animals to meet their water requirements at all times. The The German Agricultural Society (DLG) recommends one drinking trough per 20 animals and a total trough length of 6 cm per animal. However, studies indicate that this may not always be sufficient. Increasing attention to this topic has highlighted the impact of improperly positioned troughs and herd hierarchy on reducing water intake (Burkhardt et al., 2025).

Environmental conditions such as ambient temperature, water temperature, and the physicochemical composition or contamination of water also affect its taste and, consequently, the volume of water consumed.

Laboratory parameters such as haematocrit and blood albumin can indicate insufficient water intake.

Modern technology also allows assessment of water consumption in cattle. For this purpose, microchips in the form of rumen boluses are used. Some boluses can measure internal body temperature in the rumen, enabling the detection of short-term temperature fluctuations during drinking. These fluctuations can be used to infer drinking behaviour (e.g., Smaxtec).

Faecal biomarkers represent a valuable, non-invasive tool for gaining insights into pathophysiological processes in the gastrointestinal tract. They enable the differentiation between inflammatory and non-inflammatory causes of chronic enteropathies, provide indications of protein loss, and assist in monitoring disease progression and guiding therapeutic decisions. Below, we present the most important faecal biomarkers currently available in veterinary medicine.

Canine and feline intraocular neoplasia are relatively rare, when compared to neoplasia affecting other organs. Primary tumours are more common than metastatic disease.

The clinical diagnosis of intraocular tumours is often challenging. In contrast to tumours in the skin, neoplasia in the eye may not be readily visible and remain unapparent from the external surface of the eye. Intraocular tumours can also cause variable clinical symptoms, depending on the exact intraocular structures involved or affected by the mass, further complicating the clinical diagnosis.
As a consequence, even very small and/or benign tumours can have dramatic effects on the ocular function. Loss or impairment of vision, tissue destruction and secondary glaucoma are common clinical symptoms leading owners to opt for a veterinary consult. Although the impact varies depending on the anatomical location of the neoplasm, ocular neoplasia is a common reason for enucleation.

In both dogs and cats, reviews in literature identify melanocytic tumours as the most common primary intraocular neoplasm. According to the WHO classification, melanocytic tumours are divided into two groups: benign tumours referred to as melanocytoma, and malignant tumours referred to as melanoma.

In the eye, the anterior uvea is considered as most common intraocular location for development of melanocytic tumours in animals. In dogs, tumours are most often benign, but in cats, tumours are most often malignant. In contrast, melanocytic neoplasia in the posterior uvea is rare in both canine and feline species, and most tumours are benign in this location.

The unique features of the two most frequently recognized entities in dogs and cats will be discussed in more detail below.

Feline diffuse iris melanoma (FDIM)

Melanocytic tumours account for 67% of all feline primary ocular neoplasia. Feline diffuse iris melanoma is by far the most common ocular melanocytic neoplasm in cats, with limbal and atypical melanomas being uncommon melanocytic tumour variants far less often diagnosed.

Feline diffuse iris melanoma can occur in cats of any age, with an average age of 9.4 years. A breed or sex predilection has not been reported.

Feline diffuse iris melanoma is a malignant disease, with a highly variable clinical appearance, making diagnosis sometimes challenging, especially in early stages of the disease. Lesions often start as one or multiple small pigmented foci on the iris, macroscopically visible as flat black spots. These spots are referred to as iris melanosis, and are considered a benign precursor stage of feline diffuse iris melanoma.

The progression of the disease is highly variable and therefore unpredictable. Lesions may remain stable for months or even years, while some foci show very rapid progression with locally invasive growth and metastatic disease in a short time period.
This complicates clinical management as well.

Clinically, iris melanosis and early stages of feline diffuse iris melanoma are indistinguishable.
The transition from iris melanosis to malignant feline diffuse iris melanoma can only be confirmed by histological examination. In iris melanosis, melanocytes are solely confined to the superficial layers of the iridial surface. As soon as atypical melanocytes are expanding into the iridial stroma, lesions are progressed to feline diffuse iris melanoma.
In this stage, iris thickening, pupil shape changes (dyscoria) and reduced mobility of the pupil can be observed clinically.

Ear diseases in rabbits are a common reason for presentation in small mammal practice.
Unfortunately, they are also often incidental findings during clinical examinations. In most cases, otitis refers to inflammation of one or more structures of the ear and, as in dogs and cats, can be categorised as otitis externa, otitis media, or otitis interna.

Causes

Age, sex, or husbandry conditions have little influence on the development of otitis, although lop-eared rabbits are commonly affected. Due to anatomical restrictions caused by the drooping ears, stenosis of the external auditory canal can occur, leading to an accumulation of cerumen in front of the eardrum.

Restricted ventilation and increased moisture in the ear favour the development of otitis externa and possibly otitis media. Injuries, foreign bodies, ectoparasites, and ascending infections from the respiratory tract or teeth are further causes of otitis in rabbits.

Symptoms

Different symptoms may be observed depending on the underlying cause:

• Cerumen build-up in the outer ear: possibly reduced activity and responsiveness due to sound dampening.
• Otitis externa: head shaking, ear scratching, changes in the pinna (e.g. redness, warmth, discharge, swelling, bleeding), possibly aural diverticulosis (under the pinna), or a droopingear (in rabbits that normally have erect ears).
• Otitis media: may present with head tilt, facial nerve paresis or Horner’s syndrome
• Otitis interna: may include the abovementioned symptoms, as well as rolling, reduced general condition and decreased feed intake

Diagnostics

The ear examination includes a clinical examination, cytology, and, if necessary, bacteriological and mycological analyses of ear secretions (with antibiogram). If involvement of the middle or inner ear is suspected, additional imaging techniques such as X-rays or computed tomography are required. Other systemic infections are ruled out through blood tests, including differential blood count and antibody testing for Encephalitozoon cuniculi.

Further details on ear examination, cytology, and bacteriological analysis are provided below.

Clinical examination

The ear examination starts with a thorough inspection and palpation of the outer ear and surrounding area (checking for scratch marks, injuries, diverticula, or skin changes).

If the head is tilted, the eyelids and lips should always be examined carefully. Unilateral facial nerve palsy — indicated by contraction of the upper lip (Fig. 2), reduced eyelid closure, and/or Horner’s syndrome (miosis, ptosis, enophthalmos) — may suggest involvement of the middle or inner ear.
The external auditory canal is examined using an otoscope or video endoscope. In a healthy ear, gently pulling the pinna upwards (Fig. 1) usually allows visualisation up to the eardrum (Fig. 3). If material is present in the ear canal, it is important to determine whether it is merely accumulated cerumen (white deeper inside, yellowish nearer the opening) with no signs of irritation, or whether there are signs of inflammation such as redness, swelling, lesions, or liquefied secretions (Fig. 4). Potential primary causes like foreign bodies or ectoparasites should also be considered. Cytology helps in making this distinction.

Sampling

For proper sampling, an otoscope funnel, thin swabs (with transport medium), microscope slides, and cover glasses are required. Samples are usually taken from the external auditory canal in unsedated rabbits (middle ear samples are taken intra-operatively). Wrapping the animal in a towel (“wrapping”) helps to prevent defensive movements (Fig. 1).

To ensure the sample is taken as deeply as possible, the swab is carefully inserted through the otoscope funnel to just before the eardrum and gently rotated. It is then smeared onto one or two slides for cytology and subsequently placed in the appropriate transport medium tube for culture if needed. Swab samples can be stored at room temperature or refrigerated for up to 24 hours (shipment without refrigeration is possible).

It is always recommended to sample both ears ‒ even, or especially, if only one ear is affected ‒ to gain insight into the patient’s normal ear microbiome (if needed, the samples can be spread side by side on the same slide) (Fig. 5)

Ear cytology

Cytology provides important information about the composition of the secretion (cerumen or pus) as well as potential primary causes such as ectoparasites, yeasts, and/or increased bacterial numbers. For cytological preparation, the swab is gently rolled out in a thin layer on two slides. After air-drying, one slide is analysed under the microscope (condenser down, aperture closed, magnification 100–400x) for ectoparasites. The second slide is stained – for example, with Diff-Quick® ‒ and after air-drying, is also examined (magnification 100–400x; 1000x with oil immersion, condenser up, diaphragm open)

Cytology provides initial information about the type of secretion: uncoloured cerumen (Fig. 6) or clearly stained pus with DNA streaks (nuclear remnants of neutrophil granulocytes and keratinocytes), bacteria, or yeasts (Fig. 7).

The amount of bacteria (cocci, rods) and yeasts (Malassezia) can also be assessed.
An increased number of DNA streaks and bacteria or Malassezia throughout the preparation indicates an inflammatory process. Bacteria (always the same size and shape) should not be mistaken for staining artefacts. Only a few intact neutrophil granulocytes are typically found in rabbit ear preparations.

Malassezia (Malassezia cuniculi) appears round in rabbits, varies in size, may form buds, and stains deep blue (Fig. 8).

The cytological examination should be carried out prior to the initiation of therapy and repeated during follow-up. On the day of the check-up, no medication should be applied to the ear canal.

The LABOKLIN expert panels, featuring exciting topics and outstanding specialists, are extremely popular. We have selected the most important answers to your questions on the topic of lymphoma.

Our team of experts consisted of: Prof. Dr Carla Rohrer Bley, Dipl. ACVR, Dipl. ECVDI (Radiation Oncology), Master of Applied Ethics, Director of Clinical & Translational Oncology, Vetsuisse Faculty, University of Zurich, Switzerland; Dr Heike Karpenstein-Klumpp, German Specialist (Fachtierarzt) radiology/imaging and internal medicine), Zentrum für Tiergesundheit Baden-Baden, Germany; Dr Sandra Lapsina, Dipl. ECVCP, LABOKLIN, Germany; Dr Jarno Schmidt, Dr. med. vet., Dipl. ECVIM-CA (Oncology), MRCVS, German Specialist (Fachtierarzt) internal medicine, M.A. (mediation & conflict management), IVC Evidensia Tierklinik Hofheim, Germany.

Prof. Dr Rohrer Bley provides an introductory overview. She explains that lymphoma is a neoplastic transformation of lymphocytes, which can occur either locally or in a generalised form.

Different types of lymphoma are classified based on the organs affected. In dogs, generalised, multicentric lymphoma involving the lymph nodes is particularly common, while mediastinal, cutaneous, and intestinal lymphomas occur less frequently.
In cats, gastrointestinal lymphomas are especially prevalent, followed by lymphomas of the kidneys, nasal cavity and mediastinum. Another important classification is based on the cellular origin, e.g. B-cell or T-cell lymphoma.

When asked about breed predispositions, Dr Schmidt explains that, in principle, all breeds can be affected. However, certain breeds appear to be disproportionately predisposed. There are also regional differences: for example, in the USA, Golden Retrievers are frequently mentioned, whereas in Europe, Boxers, Dobermanns and Bernese Mountain Dogs are more commonly affected.

Dr Lapsina reports that prognosis is influenced by the cell type. For instance, the prognosis for T-cell lymphomas is often poorer than for B-cell lymphomas in canine multicentric lymphoma.

Moreover, the subtype can also have an impact. Therefore, it may be advisable to perform further classification of the lymphoma (e.g. via immunophenotyping using flow cytometry or immunohistochemistry) once the diagnosis has been confirmed. Dr Schmidt supports this view and adds that certain anatomical forms are associated with a less favourable prognosis (e.g. feline renal lymphoma, canine intestinal lymphoma). However, alongside aggressive (high-grade) lymphomas, there are also indolent or low-grade variants for which the prognosis may be considerably better (e.g. feline small-cell intestinal lymphoma).

The participants would like to know which findings might raise suspicion of lymphoma. Dr Karpenstein-Klumpp looks for enlarged peripheral lymph nodes in dogs. She also pays close attention to dogs with an enlarged spleen on palpation, or cats with renomegaly. In cats, she routinely performs careful compression of the cranial thorax. The otherwise highly mobile thoracic wall in cats becomes rigid in the presence of large mediastinal masses. Other potential indicators prompting an investigation for lymphoma include chronic weight loss, polyuria/ polydipsia (PU/PD), or fever of unknown origin.

Dr Lapsina notes that blood findings are generally non-specific. However, changes that should prompt consideration of lymphoma as a differential diagnosis include non-regenerative anaemia, thrombocytopenia, lymphocytosis, eosinophilia, hypercalcaemia, hyperglobulinaemia, and increased concentrations of acute phase proteins (serum amyloid A in cats, C-reactive protein in dogs).
Lactate dehydrogenase (LDH) holds a special place — it can be markedly elevated in lymphoma and may even be prognostically relevant.

Tumour markers can also be assessed. However, Dr Lapsina notes that the currently available markers are more suitable for screening in clinically healthy dogs and for monitoring during follow-up. Thymidine kinase and nucleosomes are of particular relevance.

Thymidine kinase levels increase during cell proliferation and are elevated in cases of lymphoma, but may also rise in inflammatory conditions. This marker is of interest because, in canine multicentric lymphoma, elevated thymidine kinase levels during or after treatment may indicate an early relapse — even before lymphadenomegaly becomes clinically apparent. Therefore, measuring thymidine kinase before the start of therapy can be useful for monitoring thereafter.

Nucleosomes, which are released into the blood during cell death, may also serve as a screening tool. An increased concentration in a clinically healthy dog can suggest the presence of a tumour. However, it is important to recognise that interpretation becomes challenging in dogs with fever or other clinical signs, as the marker does not differentiate between inflammation and neoplasia.

Dr Karpenstein-Klumpp provides a concise yet excellent overview of the indicative findings in abdominal sonography. In dogs with multicentric lymphoma, she often identifies an enlarged spleen with well-defined, hypoechoic areas — commonly referred to as a “moth-eaten” appearance — along with large, hypoechoic, round abdominal lymph nodes. Hepatic lymphoma, on the other hand, tends to show less characteristic changes and is often difficult to detect. Renal lymphoma in cats typically presents as renomegaly with an irregular surface and a hypoechoic peripheral rim. Large-cell lymphoma of the gastrointestinal tract in both dogs and cats is usually characterised by focal, markedly hypoechoic thickening of the intestinal wall, accompanied by complete loss of normal layering. Associated abdominal lymph nodes are generally enlarged, round, and hypoechoic. In contrast, the small-cell or low-grade intestinal lymphoma frequently seen in cats is sonographically indistinguishable from inflammatory bowel disease. The muscularis layer of the intestine is often thickened, as is also seen in inflammatory conditions, but the normal layering remains intact.
While the intestinal lymph nodes are enlarged and typically show reduced echogenicity, they do not exhibit the pronounced hypoechogenicity and altered morphology characteristic of high-grade lymphoma.

Dr Lapsina emphasises that cytology is a central diagnostic tool in the evaluation of lymphoma.
If cytology reveals a highly uniform (monomorphic) lymphocyte population and/or the lymphocytes exhibit atypia, there is a strong suspicion of lymphoma. In this context, Prof. Dr Rohrer Bley strongly advises against initiating any “ diagnostic” therapy with glucocorticoids, as subsequent diagnostic procedures — particularly cytology — are usually no longer reliable under such treatment.

Dr Lapsina offers valuable tips for performing a lymph node puncture and preparing a smear that can be reliably assessed. Ideally, the puncture should be performed without aspiration to avoid excessive blood contamination and an overly dense cellular smear. Lymphoma often releases a high number of cells, which can overlap on the slide, making interpretation difficult. A good technique is to use only the needle without an attached syringe. A smaller needle bore (e.g. 22 gauge) is recommended. The material placed on the slide should be spread very gently with a second slide, as lymphoma cells are fragile and easily destroyed by pressure, rendering them unsuitable for cytological evaluation. If multiple lymph nodes are enlarged, it is advisable to choose the prescapular or popliteal nodes for sampling.
Mandibular lymph nodes are frequently affected by oral cavity infections, which may complicate the diagnosis. Additionally, they are often mistaken for the salivary glands during sampling.

Cytology can be followed by immunophenotyping using either flow cytometry or PARR (PCR for Antigen Receptor Rearrangement).
Dr Lapsina explains the purpose and application of each method. PARR is a PCR-based test used to determine whether the lymphocytes present are derived from a single clone or from different lineages. It provides a simple yes/no answer to the question of whether the sample is consistent with lymphoma, and is primarily used when cytological findings are inconclusive. PARR is a robust method that can be performed on almost any material, including already stained cells on a slide. In contrast, flow cytometric immunophenotyping does not merely confirm the presence of lymphoma but also allows for subtype classification, which is crucial for prognosis and treatment planning. However, this method requires fresh, liquid samples. Suitable specimens include blood and cell aspirates rinsed in a 50:50 mixture of 0.9% NaCl and patient serum.
Alternatively, immunohistochemistry can be performed on tissue biopsies. This is the most reliable approach but is more time-consuming and invasive.

Now the participants are interested in the opinions of the experts on staging. Dr Schmidt reports that canine multicentric lymphoma is classified into five stages. Most dogs with multicentric lymphoma are presented in stage 3 (generalised peripheral lymph node involvement) or 4 (liver and spleen also altered). Interestingly, there is no prognostic difference between the two stages. In the case of typical sonographic findings (e.g. moth-eaten spleen), Dr Schmidt does not usually insist on a cytological examination of spleen and liver.

However, he always recommends a complete haematology, including the assessment of a freshly prepared blood smear. If many large and/or atypical lymphocytes are present, stage 5 (bone marrow involvement) is likely. The prognosis is then worse. Also important are the clinical substages a) clinically good general condition and b) clinically ill (e.g. vomiting, PU/PD, weight loss). The prognosis is significantly better in substage a). Prof Dr Rohrer Bley points out that the situation in cats with nasal lymphoma is somewhat different. Nasal lymphoma is a localised disease that can be treated with radiotherapy. Any systemic involvement should be excluded beforehand through thorough staging (thoracic radiographs, ultrasound of kidneys and abdominal lymph nodes, cytology of altered lymph nodes as well as of liver and spleen).

Dr Karpenstein-Klumpp can provide reassurance regarding ultrasound-guided punctures of internal organs. It is not that difficult. The spleen in particular is easy to reach. The sewing needle technique (forwards and backwards, not fanning) without aspiration is ideal. In many patients, the puncture is successful without complications, even without sedation. However, this should be decided after individual assessment of the patient, personal expertise, and the organ to be punctured.

The therapy depends on the type of lymphoma. The primary treatment is medication. Some types of lymphoma, such as nasal lymphoma in cats, can be effectively treated by radiotherapy (if they are actually confined to the nasal cavity). Surgical options are limited. Surgery can be used for singular skin nodules, individually affected lymph nodes, and to remove an ileus in intestinal lymphoma, but is always accompanied by drug therapy. In the case of feline renal lymphoma in particular, it is important to bear in mind that this is a bilateral disease.
The unilateral removal of one kidney is pointless.

Dr Schmidt advises that pet owners should be thoroughly informed about the side effects and risks, but without creating unnecessary fear.

As the term “chemotherapy” often leads to false associations, he prefers to speak of “drug-based cancer therapy”. As a rule of thumb, he gives the following prognosis for large-cell, multicentric lymphoma in dogs undergoing chemotherapy: 50% of dogs with B-cell lymphoma are still alive after 12 months, and in the case of T-cell lymphoma, after 7–8 months. It is important to note that these are statistical values. In individual cases, long survival times can be achieved — in some instances, even several years. A cure is possible, but rare. The use of glucocorticoids alone is considered palliative, and half of the dogs die within 2–3 months.

A complete chemotherapy cycle usually lasts 4–5 months. Most protocols include doxorubicin, vincristine, cyclophosphamide and prednisolone — the so-called CHOP protocol. For T-cell lymphomas, a protocol containing lomustine is often preferred (commonly referred to as LOPP). In cats, vincristine, cyclophosphamide and prednisolone (COP) are often used alone. The active substances are selected so that drug classes with different mechanisms of action alternate, in order to achieve the broadest possible therapeutic spectrum. Doxorubicin and vincristine must be administered intravenously, whereas cyclophosphamide, lomustine and prednisolone are available as oral medications. A purely oral “tablet-based” chemotherapy is generally less effective, as it lacks key agents such as doxorubicin and vincristine. An exception to this is small-cell intestinal lymphoma in cats.

Possible side effects include loss of appetite, vomiting, diarrhoea, and secondary infections as a result of immunosuppression (chemotherapy-induced leucopenia). Local tissue damage may also occur around the venous access site if the chemotherapeutic agent is not administered correctly. A particular concern with doxorubicin is its potential cardiotoxicity; it should not be used in patients with pre-existing cardiac conditions.
Moreover, several chemotherapeutic agents — including vincristine and doxorubicin — are con- traindicated in patients with an MDR1 gene defect.

When handling chemotherapeutic agents, the safety of the personnel involved must be ensured. These drugs should only be prepared under a specialised fume hood. Alternatively, they can be ordered from selected pharmacies that supply them in a closed system. It is crucial to provide thorough instruction on the proper handling of chemotherapeutics for both veterinary staff and pet owners. The substances can be excreted in urine, faeces, and saliva. However, it remains unclear to what extent this poses a health risk to humans or animals in contact with treated pets. Particular caution should be taken with pregnant individuals and young children. Blood samples collected shortly after chemotherapy should also be handled with care.

Dr Rohrer Bley notes that one of the distinct features of lymphoma is its radiosensitivity. Due to the typically widespread nature of the disease and/or intrathoracic or intra-abdominal localisation, radiotherapy is often not a practical option.
However, excellent results can be achieved in cases of feline nasal lymphoma. A standard protocol includes 10 sessions of radiation over two weeks.
Clinical improvement is typically rapid, with median survival times of 2–3 years. Nevertheless, systemic progression can occur later in about one-third of patients.

Radiotherapy may also be used in cases of cutaneous lymphoma, provided the solitary skin lesions are detected early, before widespread dissemination occurs, or if the disease remains confined to the oral cavity.

With regard to monitoring, Prof. Dr Rohrer Bley reports that she generally refrains from regular follow-ups. Instead, she educates clients on recognising clinical symptoms, so that patients can be presented promptly in the event of disease progression. Dr Schmidt recommends regular weighing of cats, advising owners to seek veterinary examination in cases of significant weight loss.

Dr Karpenstein-Klumpp highlights the importance of accommodating the wishes of pet owners — many prefer regular veterinary visits, and some request ultrasound examinations. Dr Schmidt confirms that owners often express a desire for routine check-ups. Dr Lapsina adds that smaller (e.g. hyperglobulinaemia, hypercalcaemia, LDH) and larger tumour markers (e.g. thymidine kinase) may also prove useful in monitoring disease progression.

Dr. Jennifer von Luckner

The transition period refers to the time from approximately three weeks before calving to three weeks after. It represents one of the most critical stages in the lactation cycle of a dairy cow, as it lays the foundation for future milk production.
Cows that navigate this phase successfully tend to show higher milk yields, improved fertility, and longer productive lifespans.

During this time, cows undergo significant hormonal, physiological, and metabolic changes as they move from the dry period into early lactation.
These changes can have a profound impact on both animal health and milk production.

As dry matter intake typically decreases during the dry period, while the energy demands of the growing foetus and the onset of lactation increase, cows enter a state of negative energy balance.
To minimise the duration of this state, it is essential to formulate a well-balanced and palatable dry cow ration. Ensuring optimal feed intake requires consistent feeding management and ample access to fresh drinking water — preferably from trough drinkers rather than small automatic drinkers.

The prerequisite for an adequate mineral supply to prevent milk fever (usually caused by hypo-calcaemia) is a good feed intake as well as a ration balanced according to the Dietary Cation-Anion Balance (DCAB). In addition, calcium and phosphorus supplementation should be planned for animals at risk or during high-risk periods.

Furthermore, hormonal changes and the stress of calving put a strain on the cow’s immune system, increasing the risk of infectious diseases in freshly lactating cows.

With the help of optimised rations, consistent feed intake, and systematic health management with targeted checks, we can guide cows well through the transition period.

How can clinical laboratory diagnostics help us with this?

Clinical laboratory tests should specifically answer the following questions:

1. Are the animals consuming enough feed, and does the ration meet their energy requirements?
2. Is the mineral supply adequate with regard to clinical and subclinical milk fever?
3. What is the immune status of the animals?

Parameters that provide information about feed intake, the metabolic situation, and the immune status of the animals are shown in the following table (Table 1):

Table 1: Overview of relevant metabolic parameters during the transition period

The determination of minerals in blood and urine – particularly calcium, but also phosphate and magnesium – is essential for diagnosing both clinical (e.g. recumbency) and subclinical forms of milk fever (e.g. labour weakness, retained placenta, abomasal displacements). Other macrominerals such as potassium, sodium and chloride are also useful for assessing nutrient supply and for ration formulation, including the calculation of the dietary cation-anion balance (DCAB).

To assess the immune status of a cow, clinical chemistry parameters such as total protein, albumin, globulins, a blood count, and acute-phase proteins are useful. In the case of inflammation, increases in total protein and globulins only become apparent after a few days. The same applies to blood count changes, such as a rise in total leukocyte numbers or shifts in leukocyte sub-populations, particularly neutrophilia.

Acute-phase proteins are more sensitive and specific markers of inflammation.
Albumin is considered a negative acute-phase protein, as the liver shifts its synthesis towards transporters, mediators, modulators, and inhibitors during the acute-phase response, leading to reduced albumin levels.

The main acute-phase proteins in cattle are haptoglobin and serum amyloid A (SAA).
An increase in these proteins in the blood is an early indicator of inflammation and is also suitable for detecting subclinical inflammatory processes.
SAA tends to rise more rapidly, whereas haptoglobin remains elevated for a longer period.

A screening focusing on the described examination points can be supplemented, as needed, with additional questions and specific farm requirements, such as evaluation of milk yield data, feed analyses, measurement of backfat thickness, trace element testing, and diagnostics of acidotic or alkalotic conditions through NSBA measurement in urine.

A few words about pre-analytics:

Pre-analytical conditions are often suboptimal in field practice. So how can they be improved?
Plan herd visits in a way that allows you to collect samples from multiple animals and ensures they can be processed at the practice as soon as possible afterwards.
During transport, store blood samples upright – keep them cool in summer and protect them from frost in winter.

Serum is suitable for most clinical chemistry tests, while EDTA blood is required to prepare a blood count. To obtain serum, collect the blood directly into a serum tube and allow it to clot at room temperature for 20–30 minutes. It should then be centrifuged as soon as possible, and the supernatant pipetted off and transferred into a neutral tube. The separated serum can be stored cooled or frozen.
EDTA blood should be collected directly into an EDTA tube, ideally after the serum sample.
The first jets of blood contain more clotting factors, which increase the risk of clotting in the EDTA sample. Swirl the EDTA tube gently several times to mix. EDTA blood may be cooled, but must never be frozen. Avoid any contamination of the serum with EDTA (e.g. by mixing up the tube lids), as this can significantly alter the electrolyte values.

Good pre-analytical practice helps prevent haemolysis, which can particularly distort mineral analysis results.

Conclusion

Effective monitoring during the transition period plays a vital role in maintaining animal health and positively impacts milk yield.

Dr. Anna-Linda Golob, Swanhild Wagenfeld

Our services relating to the transition period:

• Transition profile (including blood count)
• Transition profile + haptoglobin (including blood count)
• Transition profile + NSBA (including blood count)
• Serum amyloid A testing