A new emerging feline disease: Tritrichomonas Foetus

Tritrichomonas foetus (T. foetus) has recently been indentified as a cause of chronic diarrhoea in cats in America. In 2005, this organism has been found in pedigree cats in Scotland. Originally a venereal disease in cattle, it has now been shown to inhabit the large intestine in young domestic cats, causing chronic diarrhoea.

Diagnosis of this infection is difficult, due to its similarities with other organisms and its poor ability to survive outside the animal. T. foetus has likely been the cause of many previously undiagnosed cases of diarrhoea, due to lack of knowledge and specific tests and its similarity to other diarrhoea-causing infections.

The true extend of the T. foetus infection in the UK is inknown but recently samples have been taken at cat shows to get a better idea of the spread of the disease. In the USA, the T. foetus infection was found to be in 31% of 117 cats from 89 different catteries attending an international show. Obviously, this figure is extremely high and if this is reflected in data from the UK, then it will be a major concern to all cat breeders and owners of pedigree cats.

Catteries in which T. foetus was identified had large numbers of cats with soft motions or diarrhoea and high stocking densities, suggesting overcrowding is a significant risk factor for infection. Proximity of a cattery to agricultrural animals, feeding of raw meat, type of water source, outdoor contact or history of travel were not identified as significant risk factors.

Simultaneous infection with Giardia (another diarrhoea-causing infection) was common. Infected cats are generally young but can range from three months to 13 years. In one study done in America, 75% of positive cats were less than a year old. It is possible that kittens will not show signs of diarrhoea until after they have been re-homed. This delayed period before clinical signs develop may lead to breeders being unaware that they have a problem and are, in fact, spreading the disease unwittingly. They may also have breeding cats that do not show signs but are carriers of the infection.

In America, Abyssinian and Bengal breeds seem to be over-represented. In Scotland, I have diagnosed T. foetus in Maine Coons, Ragdolls, British Short Hairs and Bengals. Infection appears to occur via the faecal-oral route and likely occurs in young kittens sharing litter trays with the queen or litter-mates. In my experience, even kittens that have been hand-reared after 24 hours with the mother have been infected, leading me to believe infection can occur at or very near to birth. There does appear to be some natural resistance to infection, as whole litters of kittens are not always affected.

The feline T. foetus infection is characterised by intermittent diarrhoea that sometimes contains mucus and fresh blood. Diarrhoea is semi-formed to cow pat in consistency and is malodorous. Involuntary dribbling of faeces/faecal incontinence and anal ulceration occur in chronic cases. In general, cats otherwise maintain good health and body condition. A consistent feature of infection is improvement of the diarrhoea with antibiotics, with return of loose motions shortly after the drugs are finished. It should be noted that antibiotics initially improve faecal consistency but their use has been shown to prolong the course of the disease and also induce a carrier status (where animals show no symptoms but are able to infect others). Misdiagnosis of Giardia is common in cats suffering from the T. foetus infection and Giardia is commonly found in association with the T. foetus infection. Any cats that have been treated for Giardia should be re-tested for T. foetus at least 14 days after the cessation of treatment for Giardia. Although drugs used in the treatment of Giardia may improve the diarrhoea associated with T. foetus, they will not clear the infection and this results in prolongation of the diarrhoea.

In a study of the long-term outcome in 26 cats with diarrhoea and T. foetus infection, diarrhoea resolved after an average of nine months after the onset of diarrhoea (range four months to two years). Relapses of diarrhoea were common and occurred after a change in diet, travel or medical treatment unassociated with T. foetus infection. In the study, 50% of the positive cats were still positive for T. foetus two to five years after diagnosis. Spontaneous resolution of the disease is therefore possible but the animals may still be carriers and could infect others.

Up until recently, there was no cure for T. foetus infection in cats. Drug companies have been trying to develop drugs for use against T. foetus in cattle without success. Very recently, a drug used in the treatment of pigeons has shown to be effective in eliminating T. foetus in cats, although no long-term studies have been undertaken to see if this drug truly cures the condition or whether the treated cats become carriers. Of all the cats I have treated with this drug, 100% have shown return of normal faecal consistency and negative stool samples for T. foetus. Whether these cats remain free of infection is to be seen. The drug is not licensed for cats and is therefore experimental.

Diagnosis of T. foetus infection in cats is difficult. Stool samples sent to commercial labs for testing will not show a positive result, even if the cat is heavily infected. The organisms are extremely fragile and once voided from the body rapidly die. Samples taken directly from the rectum via a cotton swab need to be examined immediately (within three minutes), otherwise the tritrichomonads fail to swim and are not visable under the microscope, leading to a negative result. Special cutlure pouches can be used to transport specimens or culture the organisms and these have been shown to improve the sensitivity of the test, as they allow suvival and multiplication of the organism. The most sensitive test is a technique that identifies tritrichomonas DNA in faecal samples. Although this test is expensive and only available in the USA, it is being developed here in the UK. There are very few labs in the UK that are able to test for this desease and due to the lack of knowledge and recent identification of the disease in the UK, most vets are unaware of its presence in the UK.

I must say, the more I look for this pathogen in pedigree cats the more I find and the true prevalence of the conidtion is likely to be high. my advice to all breeders is to maintain strict biosecurity for the catteries. This should include:

 Good husbandry - avoid overcrowding and shared litter trays; maintain good hygieneTest all incoming cats for T. foetus, whether for stud, pet or breeding purposes. This is already done for FIV/FELV in most case, I hope!Avoid importing cats from the USA without a certificate from a veterinary surgeon indicating specifically that the cat is free from T. foetus.Seek veterinary attention for any prolonged cases of diarrhoea and isolate the affected cats.If multiple cats have had diarrhoea in the past, screening all cats is recommended.

As discussed above, if you suspect that T. foetus is present in your cattery it is important to act quickly and seek the right help and support. It is likely in the future that catteries will be certified as T. foetus-free, as is the case with FELV and FIV infections. As public awareness grows, potential buyers of kittens may demand testing or certification of negative status of the kitten and/or its parents. I have tested all my cats and kittens for T. foetus and can certify to new owners that they are free of this disease at point of sale.

We all need to be proactive about this disease and if you require further information or would like your cats tested, please contact me.

- Andrew Armitage, BSc BVM&S MRCVS

September 2006