ACVIM (American Journal of Veterinary Internal Medicine) compiles numerous consensus statements. These mainly deal with internal diseases of small animal and equine medicine. However, their website also contains articles on infectious diseases in cattle. The consensus statements are published in the Journal of Veterinary Internal Medicine.

Table 1: Examples of professional organisations that draw up consensus statements

Specialis societies		Focal points	Predominant species
ACVIM	American College of Veterinary Internal Medicine	Internal medicine	Small animals, horses
WSAVA	World Small Animal Veterinary Association	Broadly diversified	Small animals
FECAVA	Federation of European Companion Animal Veterinary Associations	Broadly diversified	Small animals
BSAVA	British Small Animal Veterinary Association	Broadly diversified	Small animals
ISFM	International Society for Feline Medicine	Cat medicine	Cats
ISCAID	International Society for Companion Animal Infectious Diseases	Infectious diseases	Small animals
ESCCAP	European Scientific Counsel Companion Animal Parasites	Parasites, dermatophytes	Small animals, horses
BTK	Bundestierärztekammer	Broadly diversified, antibiotic guidelines	Small animals, horses, farm animals, etc.

 

FECAVA (Federation of European Companion Animal Veterinary Associations) is the overarching European organisation in the field of small animal veterinary medicine maintains a list of consensus statements on its website and provides overview posters for veterinarians (Figure 1) on the use of antimicrobial agents in common infectious diseases and information material for animal owners on the subject of infectious diseases, antibiotic therapy and hygiene. The posters and information material can be ordered in German from LABOKLIN.

The BSAVA (British Small Animal Veterinary Association), in collaboration with SAMSoc (Small Animal Medicine Society), published a book on the responsible use of antibiotics in combination with two posters on diagnostics and empirical therapy for common infectious diseases. “PROTECT ME”, the BSAVA/SAMSoc Guide to Responsible Use of Antibacterials, is a comprehensive reference work on the subject of antibiotics in general as well as specifically focussing on diseases that are frequently encountered in veterinary practice. For example, it includes chapters on bacterial eye infections, gastrointestinal infections and urinary tract infections.

At national level in Germany, the BTK (German Veterinary Association) issues guidelines on a wide range of veterinary activities. In the field of infection medicine, everyone should be familiar with the antibiotic guidelines.

The Antimicrobial Working Group of the ISCAID (International Society for Companion Animal Infectious Diseases) develops consensus statements and guidelines specifically for infectious diseases and their management and treatment in small animals. The ISCAID consensus statements for common infectious diseases in dogs and cats are briefly presented below. As with all guidelines, they represent recommendations that have been developed from the point of view of good veterinary practice and cover many cases from practice, but can never represent all clinical disease patterns equally.

ISCAID guidelines on the management and treatment of infectious diseases

1. Handling antimicrobial agents ‒ antibiotic stewardship

Given the background of antibiotic resistance and multi-resistant germs, the conscious and sparing use of antibiotics is more important than ever in order to maintain their effectiveness in the future. Guidelines on the use of antibiotics in small animal practice (antibiotic stewardship) have therefore been defined to help practitioners provide patients with successful treatment on the one hand and avoid the development of resistance on the other. These guidelines include willingness to participate, prophylactic measures such as vaccinations, the conscious selection and use of antibiotics, the development of treatment plans and the development and sharing of knowledge. The creation of a practice’s own resistance monitoring programme can also be part of antibiotic stewardship.

2. Infections of the urogenital tract

The current guidelines on urinary tract infections were published in 2019. In contrast to the previous guidelines from 2011, infections of the urogenital tract are categorised into sporadic bacterial cystitis, recurrent bacterial cystitis, pyelonephritis and bacterial prostatitis. The topics of subclinical bacteriuria, urinary catheters, surgical interventions on the urogenital tract and drug dissolution of urinary stones are also covered. The most common cystitis pathogens are Escherichia coli (Figure 2), other enterobacteria such as Proteus mirabilis and coagulase-positive staphylococci such as Staphylococcus aureus and Staphylococcus pseudintermedius (Figure 2).

The guidelines classify each clinical picture, then provide recommendations for diagnosis and treatment, followed by information on patient follow-up.

Sporadic bacterial cystitis occurs frequently in dogs and less frequently in cats. In veterinary practice, they are often an indication for the use of antibiotics.

In the new guidelines, a shorter course of antibiotics is recommended for most of the clinical pictures described. In the case of sporadically occurring cystitis, initial treatment with antibiotics should be avoided; treatment with anti-inflammatory drugs is recommended in the first instance. Subsequently, antimicrobial therapy is started for 3 to 5 days after the results of the cultural examination and if the clinical symptoms persist. Amoxicillin and trimethoprim/sulphonamide are the first choice. In the case of pyelonephritis and bacterial prostatitis, it is important to inform the laboratory of the sampling location, as different evaluation criteria are involved.

3. Respiratory tract infections

In veterinary practice, dogs and cats frequently present with respiratory infections. The ISCAID guidelines describe various diseases such as acute and chronic upper respiratory tract infections, bacterial bronchitis, pneumonia and pyothorax. For each disease complex, the causative pathogens and suitable samples for diagnosis are described and treatment recommendations are given. Doxycycline is mentioned as the first choice for many bacterial diseases of the respiratory tract in dogs and cats.

4. Dermatology

The guidelines for superficial folliculitis and pyoderma in dogs date from 2014 and are currently being revised. Guidelines on dermatophytes and malassezia are also available. The main pathogen in canine superficial folliculitis and pyoderma is Staphylococcus pseudintermedius. Local therapy with antiseptic preparations is primarily recommended. Clindamycin, 1st generation cephalosporins such as cefalexin, amoxicillin-clavulanic acid and trimethoprim/sulphonamide are recommended as the empirical antibiotics of choice for systemic therapy.

Prohibitions on the use of certain antimicrobial agents in animals

In February 2023, new legislation (Implementing Regulation EU 2022/1255) came into force at European level, which bans the use of certain antimicrobial agents (antibiotics and antivirals) and antiparasitics in animals, as these agents are to be reserved exclusively for human medicine. Among other things, active substances such as ticarcillin, piperacillin, meropenem and imipenem may no longer be used in animals.

Summary

Clinical consensus statements and guidelines are valuable resources for veterinarians as they provide consolidated and standardised information along with expert opinion on the diagnosis and treatment of common diseases in veterinary medicine. Consensus statements are usually available online free of charge. There are overview posters available for the most common infectious diseases in small animals, which cover the diagnostic procedure and empirical treatment.

Dr. Marianne Schneider

 

Our services relating to bacterial infectious diseases
– Aerobic and/or anaerobic bacteriology
– Antibiogram for aerobic and/or anaerobic germs
– Testing for multi-resistant germs
– Blood cultures
– Numerous direct pathogen detections by means of PCR
– Aromatograms, autovaccines
– and many more…

Algae toxins in water bodies ‒ small bodies of water, lakes, and stretches of beach can be contaminated with toxins due to algae blooms, this is a serious source of danger and it is important to take public health warnings very seriously here, not only for humans but also for dogs. Dogs should always be leashed near affected waters and should also not be allowed to run or swim in the water. The danger of spontaneous ingestion is high. In some cases, small amounts of water are enough for poisoning, which may even be fatal.

The greatest danger for poisonings occurring in dogs and cats ‒ humans

Depending on the literature source, and the region studied, the statistics show that the most common causes of poisoning in dogs and cats are in fact caused by sub­stances being administered directly or indirectly by humans.

Veterinary medicinal products ‒ Improper use or overdoses of veterinary medicines result in the increased occurrence of undesirable, and severe poisonings in pets. In most cases, this is due to misuse. However, a special sensitivity for certain substance groups is also possible. For example, the known ivermectin intolerance of some herding dog breeds is caused by the MDR1 defect, for which precautionary testing can be carried out.

Human medicinal products ‒ represent a danger that is often underestimated by animal owners; depending on the literature, they are the reason for up to one-third of all reported cases of poisoning in dogs and cats. In fact, accidental administration or ingestion by the animals is rarely the main cause. Most often, a well-intentioned attempt at therapy by the owners is the cause. People from the human health sector, in particular, are known to administer or use some medicines that are perceived as harmless and commonplace for humans, to their dogs and cats, Common NSAIDs used in human medicine can be highly toxic to dogs or cats. For example, paracetamol, which is often used in humans, is strictly contraindicated in cats. There are literature references that state the lethal dose for cats to be 50 mg/kg body weight – i.e. even parts of common household tablets can have the most severe consequences. Symptoms of poisoning such as severe disturbances of the gene­ral condition, severely altered liver values, methae­moglobinaemia and methaemoglobin, oedema, and even cardiovascular disorders can occur, which are caused by severe liver cell damage and the forma­tion and accumulation of methaemoglobin. This is due to the reduced glucuronidation capacity in cats, which leads to the formation of toxic metabolites by alternative degradation pathways. If ingested, it is essential to neutralise the effects as soon as possible. N-acetylcysteine should be administered as an aid to detoxification. Liver and kidney values must be monitored and the affected animals must be stabilised.

Foods and “superfoods” ‒ since dogs and cats, in particular, are carnivores, and are evolutionarily specialised in this area, they do not have similar enzymes or degradation capabilities and are thus more sensitive to some substances than humans. Since our tree-dwelling ancestors consumed not only animal food but also many types of fruits and leaves, humans are relatively well adapted to the ingredients of many, sometimes exotic fruits, berries, etc.

In practical terms, this means that some fruits and ingredients of foods that are considered to be common and healthy for humans or are even called “superfoods” are very dangerous for dogs and cats. Here, for example, very important: Avocados – never feed them to dogs and cats. Birch sugar (xylitol), increasingly popular as a “sugar substitute” or as a sweetener in “sugar-free” products, is very dangerous for dogs. Even small amounts can lead to poisoning. Cocoa (especially dark chocolate) and grapes can also cause sometimes severe symptoms of poisoning in sensitive individuals.

Drugs (drugs of abuse) ‒ are a rare but recurrent source of poisoning. Sources can be passive smoking, accidental ingestion in the household, but also during walks, e.g. in city parks. Symptoms are usually similar to those of human consumption and can even lead to severe poisoning. Quick tests for urine available from human pharmacies can be helpful for rapid identification.

(Poison) baits, pesticides and rodenticides ‒ the saddest topic in the field of poisoning. So-called “pesticides” generally pose a great direct and indirect threat to outdoor cats and dogs.
However, a clear distinction must be made here between “normal” use against pests and the deliberate attempt to poison pets.
The use of rodenticides (poison against rodents) is more or less well-regulated depending on the country. If you let your dog and cat run free near farms, stables, or food processing plants, you should be aware that in some cases the operators are legally obliged to carry out pest control. It is important to find out where bait boxes (which should be professionally protected from access by dogs and cats) are set up so that these places can be specifically avoided.
So-called coumarin derivatives (anticoagulants) are frequently used. Due to increasing regulation of this poison category, however, the use of a very old substance, alpha-chloralose (narcotic effect), has unfortunately become fashionable again. As the active ingredient alpha-chloralose is currently only subject to limited regulation in Euro­pe, compared to the coumarin derivatives, it can easily be bought over the counter as a bait paste in DIY shops, garden centres, or online shops. Rodenticides can cause symptoms of poisoning not only through direct ingestion of the toxins but also through the ingestion of dead rodents.
These two common substance groups are best con­firmed indirectly (in the case of coumarin derivatives by checking blood coagulation and improvement by administering vitamin K) or directly (in the case of alpha-chloralose from serum or urine).
Unfortunately, poisoned bait that is specifically tar­geted at dogs or cats frequently occurs. The police or at least the veterinary office should always be informed. Although it is sometimes possible for bait material to be analysed by private laboratories, the results of a sample taken privately and not analysed by a government agency can easily be challenged in court. We recommend that you first contact the relevant authorities if you have any suspicions.

General measures in the event of poisoning or suspected poisoning

Important sources of information in an emergency:

Poison control centres ‒ the telephone number of the local poison control centre should be known to every practice. Here you can enquire about appropriate emergency countermeasures for specific poisons, as well as for animals!

You can find out more about poisoning and poisons in animals in German-speaking countries at www.clinitox.ch.

Decontamination & stabilisation

If the poison is known – treat as directed; if the poison is unknown, proceed cautiously with symptomatic therapy.

Stabilising the patient’s cardiovascular functions is the top priority. If this is assured or the patient is still alert on arrival at the practice, decontamination measures should be taken immediately to limit the transfer of toxins from the gastrointestinal tract into the organism or to accelerate possible excretion.

Depending on the patient’s condition and the toxin ingested – induce vomiting (CAVE, e.g. not with alkalis!), administer activated charcoal orally, infuse, consider gastrointestinal lavage, administer oils/paraffin oil for fat-soluble substances or soaps and many more.

Here, as usual, “the dose makes the poison”. The more that can be removed from the body quickly or is not absorbed in the first place, the better. It is important to support the organs in metabolising or excreting the toxin and the natural detoxification function. Only in a few cases are there “real” antidotes, such as vitamin K for coumarins.

Monitor clinically until the patient has recovered and preserve material for possible cause research

Once the patient has been stabilised and decontaminated, as far as practically possible, it is essential that they initially remain under observation by their owners or as an inpatient in the clinic, depending on their condition. The general state of health, but especially the functions of the liver and kidneys, should be checked repeatedly. For almost all toxins, the liver and/or kidneys are essential for excretion and can be affected by poisioning or their physiological function may need to be supported therapeutically in order to enable the toxins to be excreted quickly.

If the causative poison is unknown or if there is a general suspicion of poisoning of unclear origin and this is to be clarified in a laboratory at a later date, sample material such as vomitus (with suspected bait), serum or urine must be obtained and stored (freezer) as close as possible to the observed symptoms or before the initial treatment or examination. Urine (preferably more than 1 – 2 ml), which was obtained close to the onset of symptoms, is the most important material, especially in the case of unclear events. Most toxins or their degradation products can be detected in this material during or after the onset of symptoms; in blood or serum it is often no longer possible to detect them at this time (if in doubt, freeze serum and urine). If the owners decide to have the material analysed for toxins at a later date, this will already be available. The examination of material from animals that have not shown any clinical symptoms for some time at this point is usually unsuccessful.

Preventing poisoning by educating pet owners is the most important measure to protect dogs and cats!

Dr Simon Franz Müller

Diagnostic options for suspected poisoning:
– Large screening with blood count
– Coagulation
– Detection of alpha-chloralose
– Detection of thallium (rodenticide)
– Poison screening
– Heavy metal screening

Tab. 1: Occurrence and frequency of dermatophytes in small mammals: **** frequent, ** rare, * very rare; T.=Trichophyton, M.=Microsporum, N.=Nannizzia, A=Arthroderma; old designation depending on time of publication; Sources: Berlin et al. 2020, de Matos and Kalivoda 2013, ESCCAP 2021, Kraemer et al. 2012, Overgaauw et al. 2017, Pignon and Mayer 2011, Vangeel et al. 2000.

Type of animal	Dermatophytes
Guinea pig	T. benhamiae (T. mentagrophytes)****, M. canis*, N. gypsea (M. gypseum)*, T. equinum (M. equinum)*, M. audouinii*, A. quadrifidum (T. terrestre)*
Rabbit	T. benhamiae (T. mentagrophytes)**, M. canis*, N. gypsea (M. gypseum)*, T. terrestre*
Ferret	M. canis**, T. mentagrophytes**
Chinchilla	T. mentagrophytes**, Microsporum spp.*
Rat	T. mentagrophytes** (mainly asymptomatic carriers), Microsporum spp.*
Mouse	T. mentagrophytes ** (mainly asymptomatic carriers)
Gerbil	T. mentagrophytes **, N. gypsea (M. gypseum)*
Hamster	T. mentagrophytes**, Microsporum spp.*
African White-bellied Hedgehog	T. erinacei**** M. canis*, N. gypsea (M. gypseum)*

 

In the Netherlands, the prevalence of T. mentagrophytes in pet shops was 16.8 % (30/179) in guinea pigs and 3.8 % (8/213) in rabbits (Overgaauw et al. 2017). In another recent German study in guinea pigs, both breeding and pet guinea pigs were examined (Berlin et al. 2020). From a total of 21 private breeding herds, 68.8 % (262/381) of the animals tested positive for dermatophytes – 55.4 % of them for T. benhamiae, 13.4 % for others (7.1 % T. interdigitale, 6.0 % T. rubrum, 2.6 % T. erinacei, 2.3 % T. verrucosum, 1.3 % T. mentagrophytes). 92.7 % of all animals were asymptomatic carriers. There was no predisposition to gender. Longhaired breeds with curls (74.0 %) and Rex guinea pigs (68.1 %) were more often affected than shorthaired breeds, animals kept indoors (67.2 %) were more often than animals kept outdoors. Catteries with frequent changes in the animal population (76.0 %) were significantly more infected with T. benhamiae than animals from self-sufficient catteries (37.1 %) (Berlin et al. 2020). Although it is often described that dermatophytes are more prevalent in young animals (de Matos and Kalivoda 2013, ESCCAP 2021, Kraemer et al. 2012), this could not be confirmed in guinea pigs from breeding herds in this study (Berlin et al. 2020).

In the evaluation of 9636 laboratory examinations of pet guinea pigs, the prevalence of dermatophytes was 3.9 % (382/9636), and 36.9 % (382/1035) in animals with clinical suspicion. T. benhamiae was detected in 98.2 % of animals with clinical suspicion (Berlin et al. 2020).

Another German study from 2012 also investigated the prevalence of dermatophytes in laboratory submissions of pet guinea pigs by means of cultural examination (Kraemer et al. 2012). Dermatophytes were detected in 38.1 % (431/1132) of pet guinea pigs, of which T. mentagrophytes was detected in 91.6 % (395/431). In addition, healthy guinea pigs were sampled: 8.5 % (14/164) were asymptomatic carriers (Kraemer et al. 2012). The prevalences in pet guinea pigs have thus remained approximately the same.

Pet rabbits, on the other hand, showed dermatophytes in only 8.1 % (83/1021) in the laboratory sample evaluation of 2012, and T. mentagrophytes in 72.3 % of these (60/83). There were no asymptomatic carriers in healthy rabbits in this study (0/140) (Kraemer et al. 2012). In a Belgian study, 3.8 % (4/104) of pet, breeding and laboratory rabbits were asymptomatic carriers (Vangeel et al. 2000). In the German study, rabbits with positive fungal cultures were younger than animals with negative fungal cultures or healthy animals (Kraemer et al. 2012).

In hedgehogs, dermatophytoses are frequently caused by T. erinacei, very rarely by M. canis and Nannizzia (N.) gypsea (M. gypseum) (Pignon and Mayer 2011). In animals displaying clinical signs, T. erinacei could be diagnosed in 4 out of 5 animals. Asymptomatic carriers have been described in 11.5 % (47/408) (Pignon and Mayer 2011).

Dermatophytes are common in guinea pigs and rare in rabbits. Guinea pigs from pet shops (up to 90 %) and private breeding stock (68.8 %) are significantly more affected than pet guinea pigs (up to 38.1 %). The prevalence in asymptomatic guinea pigs varies between 3.9 % (pet animals) and 92.7 % (breeding stock) depending on the husbandry.

Who transmits it?

Dermatophytoses are zoonoses! Transmissions to humans are frequently described. During the corona pandemic, the number of human, T. benhamiae infections increased in line with the increase of keeping small mammals during the pandemic period (Uhrlaß et al. 2023). Children and adolescents are predominantly affected, which is due the often close contact with pets. Infection can be dangerous for immunocompromised people (National Research Platform for Zoonoses 2020).

Guinea pigs are the most common source of human infections (Berlin et al. 2020, Kupsch et al. 2017, National Research Platform for Zoonoses 2020, Nenoff et al. 2014, Uhrlaß et al. 2023). However, rabbits can also become potential sources of infection. In 27.3% (3/11) of affected households with dermatophyte-positive pet rabbits, the owners, in this case mainly the children, were infected (Krämer et al. 2012).
Transmission of dermatophytes from European hedgehogs and African white-bellied hedgehogs to humans also occurs (Pignon and Mayer 2011, Riley and Chomel 2005).

Transmission of dermatophytes occurs both directly and indirectly via spore-contaminated objects, bedding, brushes and combs (de Matos and Kalivoda 2013, ESCCAP 2021). Infected ferrets often live together with cats (de Matos and Kalivoda 2013). Hedgehogs probably become infected through direct contact at the time of mothering or during fights and courtship behaviour, as the clinical signs are often visible on the head often occur on the head (Pignon and Mayer 2011). High numbers of animals in a confined space increase the pressure of infection (Berlin et al. 2020, de Matos and Kalivoda 2013).

Clinical manifestation often occurs during immunosuppression, stress, other underlying diseases, parasite infestation, weaning in young animals and warm, humid climates. Injuries, cracks in the skin and increased skin moisture are conducive to infection (Berlin et al. 2020).

Typical clinical symptoms are circular alopecia, breakage of hair, dandruff, erythema, yellow crusts, and sometimes pruritus (de Matos and Kalivoda 2013). Initially, dermatophytoses often begins on the head (bridge of the nose, eyelids and pinnae) (Figure 1). Secondary pyoderma often develops and spreads to the (front) paws, claw bed and later to the whole body (de Matos and Kalivoda 2013). Hedgehogs can present with non-pruritic, scaly lesions, especially on the head, and loss of spines (de Matos and Kalivoda 2013, Pignon and Mayer 2011).

How to diagnose?

Samples for mycological diagnosis are best taken using the McKenzie hairbrush technique (Figure 2). To increase the sensitivity, it is best not only to brush the affected skin areas, but the entire animal, for 1 – 2 minutes with a sterile brush (toothbrush, cytobrush) (Berlin and Gräser 2020). In addition, some hairs including the root should be taken from the transition of the altered skin areas and sent in a sealable bag or container. By means of microscopic examination (e.g. trichogram), fungal hyphae or spores can be detected microscopically on and/ or in the hair. However, a negative result does not exclude an infection. A woods lamp can only detected infections with M. canis. However, fluorescence is only seen in about 50 % of infections. Fluorescence is caused by metabolites deposited in the hair follicles that are formed during an infection and can usually be detected 7 – 14 days after infection (Moriello et al. 2017).

False positive results can be caused by lint, topical medications, or even soap residues (Moriello et al. 2017).

Detection by means of mycological culture is carried out by cultivation on special culture media with subsequent macroscopic and microscopic differentiation. To avoid overgrowth of moulds, it is advisable to wipe the coat with an alcohol-dampened cloth before taking the sample. In addition, selective culture media are used in the laboratory to suppress the growth of contaminants. The duration of the mycological culture varies; positive findings can often be available within 1 week. In negative cases, the culture is usually incubated for 3 – 4 weeks to rule out growth.

The national consultant laboratory for dermatophytes recommends detection by PCR due to the faster analysis time of only 2 – 3 days. Differentiation of the species is possible. Since PCR also detects dead spores, therapy control by PCR is only useful after thorough removal of the spores by bath therapy and should be considered when interpreting the results. Therefore, fungal culture is recommended for therapy control (ESCCAP 2009). The histological examination of a skin biopsy by means of special staining also provides a result within a few days. However, it is only conclusive in positive cases, and is invasive – therefore not the diagnostic method of choice (Weider 2015).
Which procedure is most effective depends on the clinic, the sample collection and the study. Recent studies showed a high sensitivity of microscopy followed by PCR for visible dermatophyte lesions (Gnat et al. 2022). In asymptomatic animals, PCR is usually superior (Berlin and Gräser 2020, Nikaein et al. 2023). However, the most recent literature recommends combining PCR and culture for a reliable result (Frost et al. 2022).

Treatment

The treatment of dermatophytoses should be carried out according to current ESCCAP recommendations (combination of systemic [itraconazole] and bath therapy [enilconazole 2 × weekly]) (Berlin and Gräser 2020, ESCCAP 2009, Hein 2016, Körnig 2021). The solution should not be rinsed out. To protect against hypothermia, animals should be properly wrapped in a towel after the wash treatment.

Local treatment of affected skin areas alone should be strictly rejected because of the high zoonotic risk, which also emanates from asymptomatic animals (Berlin and Gräser 2020, ESCCAP 2009, Hein 2016, Körnig 2021).

All animals in the herd are to be treated regardless of the clinical picture. Optimally, the therapy ends after 2 negative controls. Environmental treatment (cage, house, care utensils, clothing, etc.) is mandatory alongside the bathing treatments. Cage equipment that is difficult to disinfect should be replaced with cardboard boxes etc. for the duration of the therapy.

Testing before introducing new animals into the herd is indicated, especially for guinea pigs that are often subclinically infected (ESCCAP 2009).

Conclusion

Dermatophytes can occur in almost all small mammals, but are most common in guinea pigs and hedgehogs. As asymptomatic carriers guinea pigs are the main source of human infections, especially in children, testing should be carried out on new animals that are being introduced to the herd. Selfprotection is important and must not be neglected.

Jana Liebscher, Dr. Jutta Hein

In addition to the oral ingestion of embryonated eggs from the environment, galactogenic transmission also plays a role in Toxocara cati. An infection in the last trimester of pregnancy or at the beginning of lactation can result in larvae being transmitted to the puppies in the milk. Cats can also become infected through paratenic hosts. Paratenic hosts are animals in which a parasite resides and survives, but does not develop further. In the case of Toxocara cati, rodents and birds, for example, act as paratenic hosts that have become infected with eggs. By eating infected rodents, the cat ingests the larvae, which then develop further in the cat’s body. Inadequately heated meat from farm animals (e.g. sheep, pigs, poultry) can also contain infective larvae. In contrast to Toxocara canis in dogs, there is no prenatal infection.

Zoonosis

Humans can also act as a paratenic host or false host. They can become infected, but the development and completion of the development cycle does not occur as the parasite cannot be ingested by the final host.

Transmission routes in humans:

• orally by ingestion of embryonated eggs from the environment
• contaminated water/food
• consumption of paratenic hosts (undercooked meat)

Humans can become infected by ingesting sand or soil (e.g. sandpits, parks) where cats have defecated. Contaminated water or vegetables, for example, are also described. The significance of eating raw liver or other offal from farm animals as a route of infection is unknown in Europe. There is a lack of knowledge about the significance of food-borne transmission compared to other transmission routes. Serological tests for the detection of antibodies against Toxocara in humans usually show cross-reactivity and therefore do not differentiate between Toxocara canis and Toxocara cati.

After ingestion of infectious eggs, larvae start to migrate in the human body. The clinical pictures vary depending on the localisation affected:

• Larva migrans visceralis
• ocular larva migrans
• concealed toxocarosis
• neurotoxocarosis

Prevention:

• Minimise environmental contamination with eggs
  • Collect faeces and dispose of properly
  • Treatment of infected animals
• Repeated treatment of the female and her kittens during lactation and after weaning
  • Pregnant queen
    • to prevent lactogenic transmission of larvae to kittens (e.g. emodepside once approx. 7 days before expected birth)
  • Lactating queen
    • at the same time as the 1st treatment of the kittens
  • Kittens
    • from the age of 3 weeks
    • every 2 weeks until 2 weeks after weaning
    • then monthly until the age of 6 months
• Avoid infection through food
  • no insufficiently heated or non-frozen meat
  • no prey animals
• Fencing of playgrounds, covering of sandpits, regular application of new sand or change 1 to 2x per year
• Hand hygiene
• Washing up products from the garden
• Avoidance of geophagia in children

Toxascaris leonina

Toxascaris leonina is also a roundworm in cats. Infection only occurs through oral ingestion of eggs or by eating paratenic hosts.

Ancylostoma tubaeforme

In the case of the hookworm Ancylostoma tubaeforme, the L1 larva develops after excretion of the eggs in the faeces, which hatches from the egg and develops into the L3 larva. The infective L3 larva is ingested orally by the cat. Percutaneous infection is also possible. In contrast to Ancylostoma caninum in dogs, Ancylostoma tubaeforme plays a subordinate role in larva migrans cutanea in humans.

Isospora

Isospora felis and Isospora rivolta are strictly hostspecific. Cats usually become infected by ingesting sporulated oocysts from the environment. Paratenic hosts such as rodents and ruminants can harbour infective stages (dormozoites) intracellularly in various organs.

Toxoplasma gondii

Toxoplasma gondii belongs to the protozoa (Figure 2). The cat is the definitive host. Mammals, birds and humans can act as intermediate hosts. During their lifetime, many cats become infected. Antibodies in up to 74% of adult cats have been described in the population. After the initial infection, the animals excrete oocysts for 7 – 21 days. In case of re-infection, oocysts are not usually excreted.

Transmission routes in the cat:

• sporulated oocysts in the environment
• intrauterine through tachyzoites (rarely lactogenic)
• Bradyzoites in the meat (tissue cysts) of prey or when fed raw meat

Zoonosis

Humans can become infected via various routes.

Transmission routes in humans:

• Ingestion of oocysts from the environment (soil, water, uncooked vegetables)
• Consumption of undercooked or raw meat
• Contact with infectious cat faeces
• Intrauterine transmission to the foetus on first infection during pregnancy

The consumption of undercooked or raw meat, especially pork, sheep and goat, which contains tissue cysts, is a possible source of infection. The ingestion of oocysts from soil, water or vegetables also plays a role in transmission. Pregnant women should take particular care when gardening. Transmission to the foetus during pregnancy is rare (< 0.1%). Cat faeces with oocysts are only infectious when the oocysts have sporulated, a process that takes around 48 hours. Indoor cats that are not fed raw meat pose no risk to humans. Women who have already been infected before pregnancy and therefore have a positive antibody titre are not at risk of transmitting the disease to their unborn child.

Prevention

• Daily cleaning of litter trays to prevent sporulation of oocysts (after approx. 48 hours)
• Disposal of faeces in the residual waste and not in the toilet (reduction of environmental contamination)
• Feeding cats with prepared feed
• Consumption of sufficiently heated (70 °C core temperature for 5 – 10 minutes) or previously frozen (- 20 °C for at least 2 days) meat
• Hygiene when handling raw meat in the kitchen
• Hygiene when gardening (e.g. wearing gloves)

Giardias

Giardia duodenalis belongs to the protozoa and infects a wide range of different mammals and humans. Transmission occurs via the oral ingestion of infectious cysts from the environment.

Zoonosis

There are currently 8 genotypes with different host spectra. Assemblages A and B show a broad host range and therefore have zoonotic potential. In contrast, the other assemblages appear to be hostspecific. In cats the genotype F is dominating and the zoonotically relevant assemblages only being detected to a small extent. In humans, on the other hand, the zoonotic assemblages dominate. Giardia infections in humans are subject to mandatory reporting in Germany, with 3291 cases registered in 2019 (0.004% of the German population). The low incidence of 4 per 100,000 inhabitants is clearly evident. Of the 2303 cases with information on the country of infection, 51% of the infections were attributable to foreign countries, which makes giardiasis a classic travel-associated disease. According to an analysis by the RKI from 2013, most people were infected in Asia (22%), followed by Africa and America.
The risk of transmission from cats to humans is estimated to be very low.

Prevention:

• Removal of infectious faeces
• Strict hygiene measures, especially in countries with an increased risk of infection such as Asia
  • Hand hygiene
  • Avoidance of possibly contaminated water or food
  • Boiling or filtering water from the environment

Echinococcus multilocularis

Infection with the tapeworm Echinococcus multilocularis occurs only occasionally in cats. Cats become infected by eating rodents, which act as intermediate hosts. The worm burden in a cat infection is low and only a few eggs are excreted, which signifies a low zoonotic potential in contrast to foxes and dogs. The infective eggs are extremely resistant and can survive in the environment for up to 8 months. Vectors such as flies, but also objects such as tyres, shoes and animal paws can contribute to the spreading of the eggs.

Transmission routes in the cat:

• Ingestion of intermediate hosts (small mammals) with infective stages (metacestodes) in organs

Zoonosis

In humans, Echinococcus multilocularis causes alveolar echinococcosis. Humans become infected through direct contact with infected animals or through contaminated water, soil or food such as fruit and mushrooms.

Transmission routes in humans:

• oral ingestion of the eggs
  • direct contact with infected final host
  • contaminated food, water, soil

Prevention for people in endemic areas:

• Washing or – even better – cooking low-growing wild and cultivated plants and fallen fruit before consumption
• Washing hands after contact with soil
• Caution when handling potentially infected foxes and other end hosts

Dipylidium caninum

Dipylidium caninum, the cucumber tapeworm, requires fleas, sucking lice or chewing lice as an intermediate host to complete its development cycle. By eating an infected flea, the cat ingests the infective stages (cysticercoids), which enables the tapeworm to develop into an adult worm in the cat’s intestinal tract. If eggs or tapeworm segments are detected, the cat should also be treated for fleas and it is advisable to carry out an environmental treatment. The zoonotic risk for humans is very low and occurs through the oral ingestion of infected fleas.

An intermediate host is also always required for other types of tapeworm in cats and for the cat liver fluke Opisthorchis felineus (intermediate host: fish, humans may also be the final host). Other tapeworm species include, for example, Taenia taeniaeformis (intermediate host: rodents), Diphyllobothrium latum (intermediate host: fish, humans may also be the final host), Spirometra erinaceieuropaei (intermediate host: amphibians, reptiles, birds and small mammals, humans are very rarely the accidental host), Mesocestoides spp. (intermediate host: amphibians, reptiles, birds and small mammals, humans are very rarely the accidental host).

Dr Jacqueline Csokai

Is this hypothyroidism or not?

A low serum T4 concentration does not necessarily equate to hypothyroidism. In particular, other diseases can lead to reductions. How can such a low value be checked to determine whether it actually indicates hypothyroidism or is merely reduced due to another, non-thyroidal disease?

 

Dr Astrid Wehner highlights the value of the clinical examination. If the dog does not show a typical clinical sign such as weight gain with normal feed intake and reduced performance, and if the general examination does not reveal classic changes such as thickened skin, poor coat quality, and possibly also alopecia, scepticism is indicated.

Dr Florian Zeugswetter confirms that a complete thyroid profile can help shed light on the subject. In particular, the combination of T4 and TSH is known to be extremely valuable. If T4 is low while TSH is elevated, we can be relatively certain that hypothyroidism is present. Unfortunately, in about 30 % of hypothyroid dogs, TSH is within the normal ranges.

Thyroglobulin antibodies (ATG) can also provide guidance. If they are positive, thyroid pathology is present and, in borderline cases, may reinforce the suspicion of hypothyroidism. However, this does not automatically mean hypothyroidism is present. Many dogs develop antibodies to thyroglobulin, T4, or T3 during their lifetime, but only a relatively small percentage subsequently develop hypothyroidism. However, knowledge of antibodies has another significance: T4 concentrations can be falsified by interference with antibodies. Not only a falsely high but also a falsely low measurement is possible.
Thus, caution should be exercised in interpreting T4 concentrations when ATG are detected.

Naturally, the question about the value of measuring free T4 (fT4) followed. Dr Florian Zeugswetter points out the difference between the different measurement methods. The gold standard is still the so-called equilibrium dialysis with subsequent determination of the filtered fT4 by radioimmunoassay (RIA). FT4 measured with this method is less influenced by non-thyroidal diseases than total T4. This is only partially true for fT4 determined by other methods. Since the dialysis RIA technique is now only offered by a few laboratories in the USA, we usually have to make do with the values determined by so-called CLIA methods.
We should bear in mind that these values are also influenced by other diseases and medications.

In this context, a discussion arose regarding influencing drugs. Such drugs are e.g., glucocorticoids as well as anticonvulsants like phenobarbital.

Prof. Andrea Fischer explains that we are facing big problems especially with phenobarbital. Dogs treated with phenobarbital are often clinically as sluggish as hypothyroid patients. Phenobarbital reduces T4 and can even increase the TSH concentration (but usually only within the reference interval).

Optimally, a functional test is carried out in such patients.

It is known that the TSH stimulation test is very reliable, but unfortunately too expensive for routine use. Scintigraphy is only possible in specialised centres.

Dr Astrid Wehner reports that a reinterpretation of the inexpensive and easy-to-perform TRH test was reviewed at Utrecht University. In the study, a minimum 57 % increase in TSH 45 minutes after injection of TRH (10 ug/kg i.v.) proved a physiological function of the thyroid gland, whereas the TSH increase was lower in hypothyroid dogs.
Clinical experience is still lacking to confirm these results for everyday practice. However, the panel agreed that the test appears to be very useful.
Alenka Hrovat points to the therapy test as a valid possibility in practice. However, this should not only be done on the basis of a low T4 concentration, but only if there is a well-founded suspicion.

Dr Florian Zeugswetter interjects that especially in dogs with behavioural problems it has to be

taken into account that thyroxine is a psychotropic agent. Regardless of hypothyroidism-induced signs, administration will lead to behavioural changes.
Interestingly, this can also be the reduction of activity, which can lead to misinterpretation in hyperactive/anxious young dogs.

 

Can young dogs have hypothyroidism?

Dr Astrid Wehner considers the relatively common practice of supplementing young dogs with behavioural problems with thyroid hormones, who do not show classic signs of hypothyroidism and whose T4 concentrations are usually in the normal range, to be problematic. If a young dog shows no TSH elevation, hypothyroidism is unlikely. An isolated low T4 concentration in young dogs is highly suspicious for non-thyroidal disease.

Subclinical hypothyroidism is defined as a TSH elevation with still normal T4 concentration and thus represents an early stage of thyroid disease. There are usually no signs at this stage (hence the term “subclinical”). Monitoring should be done to distinguish dogs that develop clinical hypothyroidism from those that remain euthyroid.
Unfortunately, the term is often misused to describe animals that suffer from behavioural abnormalities and have normal TSH and T4 concentrations.

There are predisposed breeds, such as Rhodesian Ridgeback or Golden Retriever, and it is possible for hypothyroidism to develop at a young age. However, these dogs should fulfil the classic diagnostic criteria (of compatible clinical signs, low T4, and elevated TSH).

Alenka Hrovat also fears that many young dogs with behavioural problems are supplemented with thyroid hormones without justification. Scientifically, it has not yet been proven that fearfulness or aggressiveness are linked to hypothyroidism.

 

The many faces of hypothyroidism

Prof. Andrea Fischer is of a similar opinion and points out that it is rather other symptom complexes from neurology where hypothyroidism can play a role as an immune-mediated concomitant disease or cause of muscle weakness. Examples are myopathy, polyneuropathy, myasthenia gravis, laryngeal paralysis, facial nerve palsy, megaoesophagus and very rarely vestibular syndrome. In addition, hypothyroidism can be a possible cause of an infarction (stroke).

 

The treatment

There is uncertainty about the new pharmaceutical act and how to deal with the manufacturer’s instructions. What to do when one manufacturer gives a once-daily dosage and the other a twice-daily dosage?

 

Prof. Wolfgang Bäumer can reassure us regarding this. As long as a dosage recommendation and not an explicit dosage specification is given in the package insert, we veterinarians are not bound by it. The preparations can be given once or twice a day regardless of the manufacturer’s recommendation.

The question arises whether the preparations for the different claims made by the manufacturer differ in their pharmacokinetics?

In this context, Prof. Wolfgang Bäumer explains that this does not have to be the case. Due to the relatively short half-life of thyroxine, twice- daily administration seems to make sense from a pharmacological point of view. At the same time, clinical signs can certainly be remedied in many cases with once-daily administration. It is interesting to note, however, that in human medicine there is a debate about avoiding changing preparations during treatment as much as possible.
Dr Florian Zeugswetter always gives thyroid hormones on an empty stomach. He is convinced that otherwise they are not sufficiently absorbed. Prof. Wolfgang Bäumer confirms in principle that absorption is better when the patient is fasting, but points out that there could be individual variations depending on the dog. Alenka Hrovat notes that the compliance of dog and owner is better when medication is given with food. She therefore prefers this variant and has few problems with the setting in everyday clinical practice. All experts agree that the chosen scheme must be maintained on the day of blood collection for monitoring.

 

What is the legal situation regarding long-term medication?

Prof. Wolfgang Bäumer points out that even a patient on a long-term medication must regularly come in for a clinical examination. What exactly is meant by “regularly”, however, is not clearly defined in the Veterinary Medicines Act. However, a corresponding presentation should be documented at least every 3 months.

Unfortunately, sending medication by post is not permitted even in the case of long-term medication!

Also, the medication may not be administered on behalf of another colleague (e.g. if the owners have forgotten the tablets on holiday) without examining the dog. However, verification of the diagnosis by requesting the thyroid findings is not mandatory.

 

Monitoring

What if the T4 concentration does not increase under substitution?

 

Dr Astrid Wehner strongly advises to take another look at the diagnosis in such a case.
Was a nonthyroidal disease overlooked? Such diseases may have led to a misdiagnosis. It is also possible that other diseases exist in addition to hypothyroidism, making the diagnosis difficult. A similar problem can occur with interference from certain medications. In addition, medications that inhibit stomach acid formation or contain calcium reduce thyroxine absorbtion, which applies to food present in the stomach.

Prof. Wolfgang Bäumer points out that from a pharmacological point of view, the time interval between tablet administration should be observed. If the time interval of 4 – 6 hours after tablet administration is exceeded, the T4 concentration will already drop significantly again.

Alenka Hrovat reminds us that the target range for T4 should be in the upper reference range.

Dr Florian Zeugswetter can tell us about the additional determination of TSH and/or thyroglobulin antibodies as part of the monitoring. A TSH measurement to check the sucess of the therapy, makes sense, if the TSH was elevated at the time of initial diagnosis. A TSH concentration in the reference range should be aimed for. The decrease in thyroglobulin antibodies during therapy has no significance with regard to the success of the therapy. However, it should be noted that the antibodies can falsify the T4 concentrations. This can play a role if the laboratory result and the clinical condition of the patient differ. Dogs with autoantibodies usually do not need more L-thyroxine than other patients!

 

Dr Jennifer von Luckner

Severe acute respiratory syndrome Coronavirus (SARS-CoV-1 & SARS-CoV-2)

SARS-CoV-1 was documented in November 2002, and SARS CoV-2 was reported in December 2019 affecting humans who had contact with infected animals in Chinese markets. Phylogenetic analyses showed great similarities between the two viruses and coronaviruses in cats and bats.

Table 1: Alpha- and beta-coronaviruses relevant to small mammals as well as human medicine

Species	Alphacoronaviruses	Betacoronaviruses
Ferret	Enteric coronavirus (FrECoV), Systemic coronavirus (FrSCoV)	SARS-CoV-1, SARS-CoV-2
Mink	Mink coronavirus 1 (MCoV)	SARS-CoV-1, SARS-CoV-2
Hamster	–	SARS-CoV-1, SARS-CoV-2
Mouse	–	Mouse hepatitis virus (MHV)
Rat	–	Sialodacryoadenitits virus (SDAV)
Rabbit	Rabbit Enteric Coronavirus (RECV), Pleural Effusion Disease Virus (PEDV) (not yet assigned)
Human	Human coronaviruses (e. g. HCoV-229E, HCoV-NL63)	Severe Acute Respiratory Syndrome-related Coronavirus (SARS- CoV-1, SARS-CoV-2), Middle East Respiratory Syndrome Corona- virus (MERS-CoV), Seasonal human coronaviruses (HCoV-OC43, HCoV-HKU1)

Source: Laboklin

They have been assigned to the Betacoronaviruses, but the exact origin and possible intermediate carriers are still unclear. However, a zoonotic origin is most likely. SARS-CoV bind to ACE-2 receptors. Primates, cats, ferrets, syrian golden hamsters and rabbits show a similar receptor distribution to humans and are therefore used as models. With the exception of older animals, ferrets and hamsters showed only mild symptoms in infection trials of SARSCoV-1 and SARS-CoV-2. For SARS-CoV-1, young mice, guinea pigs and rats were also used as models. However, despite virus replication in the tissue, they developed no or only very mild symptoms. For SARS-CoV-2, only transgenic mice with adapted receptors seem to be susceptible.

Mink are particularly susceptible to natural infection with SARS CoV-2. Mink farms in the USA, the Netherlands, Denmark and Spain have experienced major employee-introduced SARS CoV-2 outbreaks with deaths due to severe pneumonia. Proven retransmissions from minks to humans led to the culling of countless mink herds and temporary breeding bans in some countries. Ferrets appear to be much less susceptible. Natural infections with SARS-CoV-2 have been detected in asymptomatic pet ferrets in Spain (8.7 % of 71 animals by PCR, 1.57 % of 127 animals serologically) and in one case in Slovenia.

SARS-CoV-1 and -2 have also been identified in free-living rats in China and New York.
Transmission was most likely through humans via contaminated surfaces as well as sewers. There is no evidence so far that rats led to the spread of the virus. Natural infections with SARS-CoV with clinical symptoms are therefore also possible in small mammals (especially ferrets, rats, hamsters), but rare. SARS-CoV-1 has not played a role since 2004.

Infections with SARS-CoV-2 occur mainly through close contact with infected people in the same household. The incubation period is usually two days. Small mammals are asymptomatic or show mild symptoms (increased temperature, reduced activity, diarrhoea, especially ferrets and hamsters: cough, rhinitis, tracheitis, more pronounced in older animals). Diagnosis is made, as in humans, by PCR from throat swabs. Serological detection of antibodies is possible from two weeks after infection. Antiviral therapy is not available. The animals usually recover within two weeks. Prophylactically, infected people should also observe strict hygiene measures with their pets to avoid infection. So far, there are no reports on infections of humans by their pets, which is probably due to the low virus excretion in animals.

Enteral (FrECoV) and systemic coronavirus of ferrets (FrSCoV)

Epizootic catarrhal enteritis (ECE, synonym “green slime disease”) was first described in ferrets in the USA in 1993. The disease is caused by the ferret enteric coronavirus (FrECoV). ECE typically manifests itself as a mucoid green, foul-smelling diarrhoea.
However, initial symptoms can be quite non-specific (lethargy, anorexia and vomiting). The virus is excreted via faeces and saliva. The morbidity is 100 %, but the mortality is quite low at less than 5 %. Older ferrets in particular become severely ill and may die; young ferrets show only mild forms or are subclinically infected (Figure 1). Young animals thus represent a possible reservoir of the pathogen.

The systemic coronavirus of ferrets (FrSCoV) leads to a disease that was initially called “FIP-like disease” because it has many similarities to FIP (feline infectious peritonitis) in cats. It was first recorded in Spain and the USA in 2006. Affected animals first show non-specific symptoms (diarrhoea, anorexia, weight loss, vomiting, sometimes fever). Further symptoms depend on the organs affected. In the case of CNS involvement, central nervous disorders occur (especially weakness/paralysis of the hind legs). Lymph nodes are often enlarged.
The mesenteric lymph nodes in particular are clearly palpable.
Splenomegaly and renomegaly are often present. Pathology shows (pyo-)granulomatous inflammation in the mesentery, peritoneum and affected organs. However, serous effusions such as in FIP are very rare. Changes in blood parameters are very variable (non-regenerative anaemia, hypergammaglobulinaemia, hypalbuminemia, thrombocytopenia). Young animals (< 2 years) are most susceptible.
FrSCoV could also be detected in asymptomatic animals. The onset of systemic disease after infection with FrSCoV is probably caused by a multifactorial process.

The case of clinical manifestation, the course is always progressive, most animals die after a few months or are euthanised.

The seroprevalences of coronaviruses in ferrets in the USA, Japan, the Netherlands and Switzerland range from 32 – 89 % (so far no differentiation between FrECoV and FrSCoV possible). Pathogen detection by PCR from faecal samples showed prevalences of over 60 %. FrECoV was detected more frequently than FrSCoV. Mixed infections have been described. Often, no correlation between pathogen detection and clinic could be established. Despite high prevalences, both disease patterns are seen less and less. To date, there are no prevalence studies from Germany.

Diagnosis is made by direct pathogen detection using PCR. Faecal samples or rectal swabs are suitable for animals with diarrhoea and asymptomatic animals for the identification of carriers, lymph node biopsies or tissue samples for systemically ill animals. Laboklin offers PCR covering the enteric and systemic coronaviruses. The detection of antibodies by ELISA is described, but it is not possible to distinguish between FrECoV and FrSCoV. Since the titre level does not correlate with the symptoms, serology is unsuitable for diagnostics.

Treatment is symptomatic. Antiemetics, antidiarrhoeal agents, infusions, broad-spectrum antibiotics, easy-to-digest food and gastrointestinal protective agents are suitable for ECE. For systemic coronavirus infections, cortisone increase appetite. Doxycycline can help reduce secondary infections and has additional anti-inflammatory effects. Vitamins (vitamin B), minerals and antioxidants can be given to support the immune system. Immunotherapies, derived from the cat’s FIP therapy, can be tried. Prophylactically, the focus is on strict hygiene measures as well as testing of animals that are newly admitted to a herd.

Other coronaviruses in laboratory animals

Other species-specific coronaviruses have been described mainly in laboratory animals. It is unclear as to what role they play in domestic animal populations, as testing for these pathogens is rarely performed.

The mouse hepatitis virus (MHV) leads to enteritis, hepatitis, respiratory diseases or demyelinating encephalomyelitis in mice, depending on the virus strain, but can also be completely absent. In human medicine, it is particularly interesting for research into hepatitis, multiple sclerosis and SARS, for example.

Sialodacryoadenitits virus (SDAV, rat coronavirus) causes respiratory diseases (rhinitis, tracheobronchitis, pneumonia) in rats associated with inflammation of the salivary and lacrimal glands.

Rabbits can also be infected with coronaviruses. Pleural effusion disease virus (PEDV) leads to pleural effusions, cardiomyopathy, mesenteric lymphadenopathy and multifocal necrosis of various organs. The pathogen has so far only been found in laboratory animals in North America and Europe. Rabbit enteric coronavirus (RECV) causes enteritis, especially in young rabbits. Apart from laboratory rabbits, it it also plays a role in rabbit farms in Europe and the USA.
In North America, the seroprevalence is between 3 – 40 %.

Conclusion

FrECoV and FrSCoV are particularly relevant to the veterinarian and should be considered in ferrets as a differential diagnosis for diarrhoea and/or systemic disease. SARS-CoV-2 infections should be taken into consideration when respiratory infections suddenly occur in ferrets, rats or golden hamsters in households with currently Corona-infected individuals, as the infection occurs via humans.

Dr. Ekaterina Salzmann, Dr. Jutta Hein, Jana Liebscher

Since disease patterns and clinical symptoms cannot necessarily be traced back to a single bacterial strain or species, diagnostics focus on the measurement of entire functional bacterial groups. From studies, some bacteria and bacterial groups have been identified in dogs and cats that can be used as marker bacteria for a dysbiotic state of the intestine. The detection of the marker bacteria by molecular biological methods can provide information about the colonisation resistance. On the other hand, the observation of individual functional bacterial groups, such as SCFA-forming or mucosa-protective bacteria, can allow conclusions to be drawn about the condition of the mucus layer and the energy supply of the intestinal epithelial cells.

However, it should be noted that the causes of dysbiosis can be very diverse and the disturbance of the bacterial balance has a direct influence on the barrier function of the intestinal wall. Thus, the determination of further parameters can be helpful to look at the condition of the intestinal barrier in more detail (Figure 1).

Faecal biomarkers for the assessment of intestinal mucosa and digestive performance

In addition to the marker bacteria, the following biochemical parameters may supplement the dysbiosis profile:

• Calprotectin – is well suited as an inflammatory marker in differential diagnostics for a number of diseases of the gastrointestinal tract (e.g. IBD or other inflammatory bowel diseases). Likewise, it can be used to monitor the course of therapy and detect recurrences in these diseases.
• Alpha-1-antitrypsin – can be used as a marker of protein loss through the intestine. However, it should be noted that this is not a marker specific for inflammatory bowel disease. Elevated levels occur in other gastrointestinal or systemic diseases that result in increased intestinal permeability (“leaky gut”).
• The concentration of canine pancreatic elastase 1 – directly reflects exocrine pancreatic A deficiency in pancreatic elastase can lead to digestive problems and malnutrition. A low value in the faeces indicates a lack of digestive enzyme production. Decreased precaecal digestive efficiency also leads to increased flooding of fats and proteins into the colon. This shifts the milieu in favor of potentially detrimental germs and may favor the development of dysbiosis.

Another biomarker, secretory IgA (sIgA), can provide information about the burden on the intestinal mucosa and will be newly offered in the dysbiosis profile for dogs and cats from 01.07.2023.

Significance and function of the sIgA

The antibody sIgA, which is found primarily on mucous membranes, serves as a first line of defense against pathogens that can enter through the respiratory tract, gastrointestinal tract or skin. As an important component of the GALT, it binds to potentially harmful microbes or antigens, preventing them from docking or damaging the intestinal wall.

The relationship between the gut microbiome and sIgA is not yet fully clarified, but the microbiota has an impact on the GALT and thus on the formation and function of sIgA. On the one hand, it promotes the maturation and activation of plasma cells that produce sIgA. On the other hand, sIgA modulates the composition and activity of the intestinal microbiota by selectively binding or inhibiting certain microbes. This creates a symbiotic relationship that is important for the maintenance of the intestinal barrier and mucosal immunity.

sIgA is an important diagnostic marker for various diseases of the gastrointestinal tract, such as chronic inflammatory enteropathy or leaky gut syndrome. The determination of sIgA in the faeces can provide information about the functional capacity and the of the intestineassociated immune system.

• Decreased detection of sIgA may indicate impairment of the intestinal barrier and weakening of the local immune system.
  This may be associated with increased susceptibility to intestinal disease, increased susceptibility to infection, allergic reactions, or immunosuppressive conditions.
• Elevated sIgA may indicate a particular strain on the intestinal immune system, which may be caused by acute or chronic inflammation of the intestinal mucosa. Possible conditions include colitis, IBD or parasitosis.

The determination of sIgA in faeces is a simple and non-invasive method to assess the local immune status in the intestine. However, it should always be interpreted in combination with other clinical and laboratory parameters to make a correct diagnosis.

Case study

“Leila” is an 8-year-old female boxer who has been suffering from recurrent diarrhea (Figure 2), flatulence and loss of appetite for several months.
A dysbiosis profile was obtained from collected faeces (Figure 3). The analysis revealed elevated levels of sIgA and calprotectin. This indicates inflammation of the intestinal mucosa as well as a strong stress of the local immune system. Analysis of marker germs revealed decreased diversity of the microbiome. The intestinal score of 5.0 was in the abnormal range, indicating a dysbiotic state. A closer look at the marker bacteria groups revealed a slight to strong reduction to the reference values of F. prausnitzii, Turicibacter spp. and Blautia spp. These species belong to the Firmicutes phylum and play a crucial role in the energy supply of intestinal septate cells as SCFA producers or SCFA recyclers.

Proteobacterium E. coli, on the other hand, was elevated compared to the reference range. This is observed in dogs in connection with gastrointestinal disorders. In addition to displacement of mucosa-protective bacteria, the strong immunogenic effect and adverse metabolites may contribute to irritation of the intestinal mucosa. Furthermore, the intestinal milieu is thus shifted in favor of pathogens.

By switching to an easily digestible feed with the addition of prebiotics, the growth of mucosal protective bacteria can be promoted while inhibiting the spread of detrimental bacteria. This effect can be further enhanced by the additional use of probiotics. Consequently, the enterocytes are again better supplied with energy and the consequences of irritation by harmful bacterial metabolites decrease.

If necessary, the therapy can be supplemented by the addition of anti-inflammatory drugs.

Dr Jennifer Scherzer

Tip: It is important to obtain swabs without transport medium (from the eye/oral cavity and/or throat) for PCR and swabs with transport medium (from the same locations) for bacterial culture before starting treatment in patients suspected of having URTD to ensure comprehensive diagnosis.

S. canis and S. equi ssp. zooepidemicus are described as commensals of the mucosal surfaces of healthy cats. Under certain conditions, such as stress, high infection pressure or immunosuppression, these agents can also cause primary diseases ranging from sinusitis to pneumonia, especially in larger groups of cats (breeding facilities, animal shelters). S. equi ssp. zooepidemicus gained attention after an outbreak in a shelter in Israel in 2010, where it was isolated from a large proportion of deceased cats with purulent nasal discharge, cough, sinusitis, dyspnea and pneumonia. Both species mentioned above belong to the beta-haemolytic Streptococcus group and can be cultured easily. They also play a role as secondary agents, as do Staphylococcus spp., Pasteurella multocida and Escherichia coli (E. coli).

Tip: Additionally, testing for FeLV (Feline Leukemia Virus) and FIV (Feline Immunodeficiency Virus) status is useful, because animals with retroviral infections are often predisposed to URT infections and may have more severe courses of disease.

Lower respiratory tract infections (bronchitis/pneumonia) can also arise secondarily from upper respiratory tract infections. Furthermore, bacterial secondary infections are common even in non-infectious primary causes (e.g., anatomical problems of the larynx/trachea, allergies). However, primarily Bordetella bronchiseptica and Mycoplasma felis have been described here, which can lead to chronic bronchopneumonia/bronchitis. Clinically, bronchitis is usually manifested by coughing. Bronchoalveolar lavage (alternatively: tracheal wash) should be performed in this case. Both secretions can be used for PCR as well as bacterial culture.

Patients showing symptoms of cough, fever, lethargy, and anorexia may suffer from pneumonia. Pneumonia is very rarely caused by bacterial infections or the classical feline respiratory viruses, but is more often caused by aspiration, injuries, or underlying conditions such as diabetes mellitus. Bacterial infections are much more commonly secondary at this stage. The responsible pathogens are equivalent to those causing URT infections.

Pathogen (name of the PCR profiles)	total (n)	PCR positive (n)	PCR positive (%)
FHV (respiratory tract I-IV)	7676	851	11
FCV (Airways I-IV)	7676	2127	28
Chlamydia (respiratory tract I-III)	7053	413	6
Mycoplasma felis (respiratory tract I+II)	6607	3007	46
Bordetella bronchiseptica (respiratory I)	3718	104	3

Table 1: Detection frequency of the 5 primary pathogens of the feline rhinotracheitis complex by PCR (respiratory profiles I-IV) in 2022
Source: Laboklin

In 2022, we evaluated 7676 respiratory PCR profiles (PCR profiles I-IV), each containing the five primary feline respiratory pathogens in various combinations. FHV-1 and FCV were identified as the most important primary pathogens, represented in all of the five profiles. FCV was detected in 28% and FHV-1 in 11% of all tests. Chlamydia was detected in 6% of the samples, whereas Mycoplasma felis was found in 46%. Only 3% of the samples were tested positive for Bordetella bronchiseptica (Table 1). Infections occured either as single or combined infection.
In addition to PCR profiling, bacterial culture (BC) was requested in 1044 cases (Figure 1). In these examinations, the most frequently detected pathogens were Pasteurella multocida (48%), haemolytic staphylococci (21%) and E. coli (15%), which could be isolated individually or in combination. Only 5% of the bacterial culture showed no bacterial growth (negative).
When performing both bacterial culture and one of the four respiratory profiles (n=645),
62% of the samples were positive for at least one of the 5 PCRs (FHV-1, FCV, Chlamydia, Mycoplasma felis, Bordetella bronchiseptica). Of these 645 samples, 42% were positive for FCV and 20% were positive for FHV-1. Using these two primary pathogens as an example, we investigated which bacterial pathogens could be identified in bacterial culture (Figure 2
and 3).
Beta-haemolytic streptococci, including S. canis and S. equi ssp. zooepidemicus, which are among the possible primary pathogens in URTD, were detected rarely and therefore summarised under “Others”, the same applies to Bordetella bronchiseptica.

Identical to Figure 1 Pasteurella multocida, haemolytic staphylococci and E. coli were identified as the most common pathogens. In combination with the primary viral pathogens, these bacteria often require therapy.

Conclusion:

PCR is the method of choice for detecting the five most important primary pathogens in cats with respiratory infections, as it is reliable and fast. Bacterial culture is also useful in most cases to identify secondary infections that require antibiotic therapy and to treat them successfully using an antibiogram. Especially in case of chronic respiratory problems or lower respiratory problems both investigations are recommended. To be emphasised are a detailed anamnesis, appropriate sample material, and the interpretation of the test results in the context of the clinical presentation.

Dr. Eva-Maria Klas
Dr. Marie-Louise Hoffknecht

Microscopic evaluation of otic exudate

Evaluation of otic exudate is used to detect parasites (direct microscopic exam) and infectious agents (cytology).

Direct microscopic exam
A sample of otic exudate obtained with a swab or curette is placed in a drop of oil on a slide. The exudate is dispersed in the oil and a coverslip applied. Under 4x magnification, the presence of Demodex or Otodectes diagnoses the primary cause of otitis.

Cytology
Depending on the type of exudate, otitis are classified as ceruminous, bacterial, yeast, mixed or purulent.

Ceruminous exudate consists of cornified epithelial cells and lipids and may contain a small number of coccoid bacteria and yeasts (up to 5 yeasts and 25 coccoid bacteria per 40X field may be expected). The presence of rod bacteria is always considered pathological.

The proliferation of bacteria and/or Malassezia characterises otitis into coccoid, rod or mixed bacterial; Malassezia or mixed otitis (bacteria and Malassezia).

The presence of inflammatory cells (neutrophils or neutrophils and macrophages) defines purulent otitis (Fig. 4). A purulent exudate may be observed in pemphigus foliaceus and infectious otitis, especially otitis with rod-shaped bacteria.

Bacterial culture and sensitivity

Initially, it is unnecessary since with topical treatment, the antibiotic concentration to which the bacteria are exposed is much higher than that which can be obtained systemically.

When to perform culture and bacterial sensitivity?

• When the antibiotic initially selected doesnot resolve the infectiony
• Chronic or recurrent otitis in which severalantibiotic treatments have been usedy
• Presence of rod-shaped bacteria oncytologyy
• Otitis media

Never use quinolones without justified cause, that is when an antibiogram demonstrate resistance to first-choice antibiotics.

Other diagnostic tests useful in otitis

In cases where middle or inner ear involvement is suspected, imaging techniques should be used. Computerised axial tomography (CAT) allows visualisation of the eardrum, assessment of the contours of the tympanic bulla and detection of the presence of bony proliferations and osteolysis. Magnetic resonance imaging (MRI) differentiates between fluid and soft tissue but does not detect bone changes easily.

Treatment

Failure to treat all the causes and factors invol-ved results in chronic or recurrent otitis externa with proliferative changes that may require aggressive surgical treatment.

It is crucial to control inflammation and its cause. Inflammation and exudates make an ideal environment for the proliferation of bacte-ria and Malassezia. Topically applied corticoste-roids are usually enough to control inflamma-tion, but oral administration may be necessary if severe inflammation occurs. Topical administration is sufficient and more effective if antibiotic or antifungal treatment is necessary. Systemic antibiotics or antifungals are not required in otitis externa unless there are concurrent otitis media.

Thorough cleaning of exudates is crucial. If uncomplicated ceruminous otitis using otic cleansers. If severe otitis with intense microbial growth, rod-shaped bacteria, profuse or purulent exudate, or biofilm formation, performing a thorough cleaning with a video-otoscope and under general inhalation anaesthesia is ideal.

Dr. Carmen Lorente Méndez,
DVM, PhD, DipECVD