Colitis refers to inflammation of the large intestine. It can be caused by infection (with bacteria such as salmonella or campylobacter), cancer or parasites, but more frequently is just associated with non-specific inflammation. In some cases the rest of the gastrointestinal tract can also be inflamed.

Signs of colitis 

The most obvious sign of colitis is the production of small amounts of soft faeces. The cat may strain on the litter tray for some time and passing faeces can be very painful, so cats may cry out. There is often blood and mucous in the faeces. Usually the faeces are reasonably formed, but they can be quite liquid and if there is also a problem in the small intestine, the diarrhoea may be watery.

The disease is often associated with a reduced appetite and vomiting. The cat may have lost weight, especially if it is also suffering from small intestinal disease or if a cancer is present.

Diagnostic tests 

Your veterinary surgeon may suspect a large intestinal disease the basis of clinical signs and a physical examination. Further tests will be necessary to determine the underlying cause.

Analysis and culture of faecal samples is important to identify parasites and infectious diseases. Several faecal samples may need to be examined to find the offending bacteria or parasite because the cat may not be shedding it into the faeces all the time.

It is also important to test for feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV), as infected cats can have colitis as a result of suppression of the immune system by these diseases.

If a parasitic or infectious cause has been ruled out, further investigation will be necessary. This usually needs to be done under general anaesthetic. Radiography (sometimes using a contrast medium), ultrasonography, endoscopy or surgical biopsies may be necessary to find the underlying cause of the disease.

Treatment 

Treatment depends on the cause of the disease. If it is the result of a bacterial infection (uncommon), then antibiotics will be required - the cat may also have to be isolated from other cats. If it is a parasitic problem then the cat, and any other cats in the household, will need to be wormed with an appropriate preparation. Drugs or surgery may help in the event of other diseases.

In most cases, a special diet can fed - the use of hypoallergenic diets (diets with only one protein source), easily digestible diets and diets with added fibre have been shown to be helpful.

Prognosis 

The prognosis for cats with colitis depends on the underlying disease and the severity of the colitis itself. Many cases respond very well to appropriate therapy, although the signs can be recurrent in some cats.