Diarrhoea is a relatively common reason for owners to present their cat at a veterinary surgery. There are many underlying causes, including parasitic, bacterial, viral and dietary intolerances, and often, affected animals will respond well to empirical treatment without the need for further testing. However, Tritrichomonas foetus doesn’t respond to treatments that may be used to tackle other parasites. Asking for this parasite to be tested for can lead to early diagnosis and therefore, a better outcome for the affected animal.
What is tritrichomonas foetus?
Tritrichomonas foetus is a single-celled protozoan parasite that causes chronic diarrhoea in cats, primarily affecting younger animals, less than 12 months old, however, any age of cat can potentially be a carrier and can develop clinical signs of disease. High population density appears to be a significant risk factor in contracting this disease, with purebred cats living in, or being rehomed from, multi cat households being overrepresented in those being diagnosed.
How is this disease spread?
Infected or carrier cats will shed trophozoites in their faeces. Transmission occurs primarily via the faeco-oral route, although this organism can survive outside the host for hours to days if kept moist, so potentially ingestion of contaminated food or water could lead to infection. Social grooming , contact with contaminated bedding, dirty litter trays, and ingestion of slugs can all lead to consumption of T. foetus trophozoites.
What clinical signs are seen in infected cats?
T. foetus is an important cause of chronic diarrhoea, particularly in younger cats. It localizes primarily within the large intestinal tract, although the distal small intestine can also be affected. Colonisation of the large intestines will lead to signs of colitis due to the neutrophilic and/or lymphoplasmacytic inflammation observed. Owners may report semi-formed to liquid faeces being passed, possibly with increased frequency, containing fresh blood and mucous. Anal inflammation and ulceration may be seen as a consequence of the chronic diarrhoea, with faecal incontinence observed in some cases. In chronic cases, where a cat is straining frequently, rectal prolapse may be noted. As with many chronic diseases, general signs of ill-health may be observed, including weight loss and poor coat condition.
Are other animals at risk of contracting this disease?
There are reports or T. foetus infecting puppies, and it is also a common cause of fertility problems in cattle.
Is this disease zoonotic?
Rarely, T. foetus has been found to cause disease in humans that are immunosuppressed. Precaution should be taken with basic hygiene around cats to prevent infection with T. foetus, or other diseases that cats can harbour.
These precautions can include:
- Thorough hand washing after cleaning out litter trays or handling cat faeces.
- Cat bites or scratches should be washed with a suitable antiseptic solution as soon as possible, with medical advice sought if necessary.
- Immuosuppressed individuals should ideally not handle the cat litter tray contents and should wash their hands thoroughly after handling. If T. foetus is diagnosed, anyone with a weakened immune system should consider re-homing that cat until treatment has been administered and the infection has resolved.
How is tritrichomonas diagnosed?
While there may be certain things in the history, signalment and clinical signs that would raise suspicion of this infection, a definitive diagnosis cannot be reached without carrying out tests on the faeces.
Direct light microscopy of faecal smears may be carried out to look for the organisms, however, this test is relatively insensitive, detecting only 14% of cases, and other organisms can look similar, e.g. Giardia and Pentatrichomonas hominis. Care needs to be taken to accurately identify the organisms visualised as treatment plans will differ. Samples need to be fresh, with sensitivity decreasing in samples where contaminants are present, or antibiotics have been administered.
Faecal culture can also be performed; however, false negative results are common as the organism may not survive the time it takes to transport the sample to the laboratory. The most accurate test, with the highest sensitivity and specificity, is a PCR (polymerase chain reaction) which detects genetic material of the organism, whether alive or dead.
What are the best treatment options for this disease?
Different treatment regimes will work for different cats.
In some cases a simple change of diet, to a highly digestible or high fibre diet, along with probiotics, will be enough to control clinical signs.
If clinical signs persist, then treatment with an off-license medication called ronidazole could be considered by your veterinarian. More commonly used anti-protozoal drugs are unlikely to be effective due to organism resistance, while use of other antibiotics is also unlikely to resolve the underlying problem, and ultimately lead to prolonged shedding of the organism.
Ronidazole is available from your vet if a positive result is obtained. Possible side effects can include signs of neurotoxicity, lethargy, reduced appetite, ataxia and, in rare cases, seizures. These side effects are likely to resolve, in most cases, once treatment is discontinued. Recurrence of clinical signs is possible once treatment has finished depending on the severity of infection and host response to disease.
Can infection be prevented?
Unfortunately, there is no way of preventing your cat from being exposed to this organism. There is also no preventative treatment and no vaccines available. Things you can do that can lower the chance of infection include:
- Regular and fastidious cleaning of litter trays, food and water bowls.
- Using trusted boarding facilities that are cleaned regularly and not overcrowded will help to prevent your cat coming into contact with T. foetus.
- Regular monitoring of your cats’ faeces, and assessment by your vet if your cat develops persistent diarrhoea.
- Testing the faeces of any new kittens or cats that you bring into your home.
What is the long-term outlook for a cat that tests positive for disease?
In most cases, long-term prognosis is good for cats that get diagnosed correctly and, therefore, are given the right treatment for this disease. However, recovery from the clinical signs caused by this organism can be slow, with an average of nine months from start of treatment to resolution of the diarrhoea. Occasionally cases can take up to two years, or longer to recover, with cats sometimes found to shed the organism in their faeces for months following the clinical signs resolving. Introduction of naive animals should be avoided if possible.
Please call our customer services team for further information on: 01829 781855.