Tritrichomonas Foetus in Cats

Tritrichomonas foetus is a microscopic single-celled organism that can live in the large intestine of cats, most often causing persistent diarrhoea that may contain mucus or small amounts of blood. It spreads through direct contact with infected faeces, so it tends to be seen more commonly in young cats from multi-cat environments such as breeding catteries or shelters, though cats of any age living in any setting can be affected. Some cats carry the organism without showing signs at all. Owners typically notice loose or semi-formed stools that persist for weeks or months, sometimes improving briefly before returning. The cat often remains otherwise well — eating normally, maintaining weight, and behaving as usual — which can make the pattern puzzling. In some cases the diarrhoea resolves on its own over time, while in others it continues or recurs. This page explores what signs may appear, what is happening in the intestine when this organism is present, how it can be identified through testing, and what approaches exist for managing the condition. The goal is to help you understand the range of possibilities and what conversations may be useful as you and your vet work through the picture your cat is showing.