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Tritrichomonas infection

Humbug’s Story and Tritrichomonas foetus infection in cats

Humbug was a young, fun, boisterous Black and White eleven-month-old cat. He was beautifully and unusually marked with clear Black and White stripes across his back, hence his name “Humbug”. 

Humbug was brought in to see me for a check-up as he had been having regular bouts of smelly, watery diarrhoea with some blood and mucous noted, over the past couple of months. He was very bright and mischievous; however, his diarrhoea was now becoming a worrying problem for his owners. He shared a home with five other cats, and he was the youngest and naughtiest member in this “multi-cat” household. His owners had been trying all sorts of different diets over the past few weeks to try to settle down his symptoms but to no avail.   

On examination he was very bright, and he had a normal rectal Temperature, which was a challenge to record as he was very wriggly, and his bottom was obviously a bit tender after his recent diarrhoea episodes.  He did have a "gassy" feel to his tummy, and he had lost a little weight. I suggested that we run some specific tests to try to come to an accurate diagnosis here. His owners were concerned and worried that this may be contagious to the other cats in the household. I suggested a direct faecal swab, a full faecal culture test to be sent to the Laboratory on freshly passed faeces and I took another faecal swab from him for a specific ‘PCR’ test for Tritrichomonas foetus infection.   

Humbug's -house test was suspicious, and his Laboratory tests did come back confirming that he was indeed positive for Tritrichomonas foetus infection.   

Tritrichomonas foetus is a highly motile, flagellate, protozoan parasite, that can reside in the large intestine of cats where it causes an inflammatory response in the colon, causing a large bowel diarrhoea. It is specific to cats, distinct from other Tritrichomonas species, and is not considered to be zoonotic ( i.e. it cannot be transmitted from animals to people). Infection is most common in young cats from multi-cat households. Affected cats show frequent, watery, foetid diarrhoea, often with mucus, fresh blood, and straining, but remain bright. Diagnosis of infection is usually based on direct microscopic examination of freshly voided faeces, full faecal examination, and culture, to rule out other causes of diarrhoea, and PCR testing. There is a specific antiprotozoal treatment for Tritrichomonas infection, which should be used under very careful Veterinary supervision. The clinical signs can be self-limiting in untreated cases, however without treatment this may take many months to resolve, and cause weight loss and dehydration. In multi-cat households Tritrichomonas foetus is transferred from cat to cat through use of a shared litter boxes. Cats step in soiled litter affected with the parasite and then will become infected themselves when they groom. Tritrichomonas foetus then reproduces in the infected cat’s intestinal tract. Often there are no outward signs or symptoms of Tritrichomonas foetus in healthy, adult cats. Younger cats tend to display symptoms of infection more frequently.   

Humbug was given a specific treatment to treat the protozoan Tritrichomonas infection, along with an advised prescription gastrointestinal, digestive diet and probiotics to aid in encouraging a healthier bowel flora.   

During his treatment Humbug was kept separate from his housemates who were all also carefully checked over and tested for Tritrichomonas shedding. The older adult cats in his household were not showing any symptoms of diarrhoea, however two of his adult housemates did have a positive test and were then treated accordingly. Transmission occurs via the faecal-oral route so keeping the affected cats separate until treated, and cleaning and changing litter trays daily were particularly important to clear the infection from the household. Humbugs owners were very compliant, they loved their cats and wanted to get this infection under control. They carried out the daily cleaning using strict hygiene wearing gloves, as while Trichomonas has not been found to be transmissible to humans’ sensible precautions should be taken. So, wearing disposable gloves while changing the litter box, cleaning hands, and the surrounding area thoroughly and regularly are standard recommendations.   

Humbug’s owners did eventually have success in clearing the infection from their cat family, thanks to our treatment advice and guidance. All the cats were reconciled once the household checked clear and they were all then kept on an advised easily digestible, gastrointestinal diet and probiotic treatment long-term. Humbug was back to normal and so happy to be back with his friends again!   

Do contact your Vet for good professional advice if you are concerned about diarrhoea in any age of cat.


Alison Laurie-Chalmers,   

Senior Consultant,   

Crown Vets 

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