Why does my cat have diarrhoea?

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Many cases of diarrhoea are mild and short-lived, only lasting for a few days, and will resolve on their own.

(Q) My one-year-old cat has had diarrhoea for about a week now, although he is making it to his litter tray and it's only once a day. There are no worms or blood in his stools, he's eating his usual dry food, and he seems fine in himself. I've cut out his wet food and treats to see if this helps, but it hasn't so far. What could be causing it?

(A) Vet Elise Robertson says: In general terms, diarrhoea can be caused either by a disease of the intestinal tract itself (primary intestinal disease), or less commonly by a disease affecting another organ (systemic disease) that in turn is affecting the intestine. The majority of cases of diarrhoea are due to primary intestinal disease.

Many cases of diarrhoea are mild and short-lived, only lasting for a few days, and spontaneously resolve on their own. However, where the diarrhoea is severe or prolonged, a visit to your vet may be required in order to determine the underlying cause and decide on appropriate treatment.

Some of the more common causes of diarrhoea in a cat of this age may include a sudden dietary change/intolerance, infectious causes (including viruses, bacteria and parasites) or Inflammatory bowel disease - this is a complex disease because inflammation within the bowel can result in chronic (longterm) persistent or intermittent diarrhoea and/or vomiting in cats.

If the diarrhoea has developed recently, is relatively mild, and the cat is still bright and alert, your vet may simply suggest symptomatic treatment to see if the problem resolves.

If not, or if the diarrhoea is more serious, further investigations may be warranted.