Feline Colitis

How many times have you been presented with a cat with diarrhoea? For anyone who’s ever owned a cat, you’ll appreciate this problem is certainly one you want resolving as soon as possible. It’s unpleasant for everyone and especially for the patient.

Posted: 29 May 2019

Feline Colitis


Colitis, or inflammation of the colon, results in a reduction in the amount of water and electrolytes which are absorbed, as well as suppressing the normal mixing contractions. The end result is that the intestinal contents are voluminous and are passed out without control. Look for;

  • Increased urgency
  • Tenesmus – animals are unsettled and constantly straining
  • Frequent defecation - small stools
  • Mucus and fresh blood (haematochesia)
  • Incontinence – cats will often defecate outside the litter box
  • Vomiting – occasionally associated with colitis
  • Pain when defecating
  • Weight loss – this is less common

Inflammation of the colon may be acute or chronic, and for many patients, the original cause is unknown. When looking for a cause, think of bacterial, parasitic, fungal, dietary, stress induced or allergic triggers.  

The investigation

Initially, you need to determine if the problem is primary or secondary in origin. Perhaps it’s associated with a gastrointestinal complaint or perhaps a systemic or metabolic disease? You also need to find out if the diarrhoea is from the large or small intestine, the clues of which will often be found in the history.

The standard investigation of feline diarrhoea would be;

  • History – ask lots of questions
  • Examination – be thorough to ensure you don’t miss anything important
  • Blood tests – perform a complete blood count, full biochemical profile including electrolytes. Also measure folate and cobalamin
  • Urinalysis – check for protein, SG and blood

In early cases, with few signs and no obvious debilitation, patients are often treated symptomatically, using electrolytes, dietary management (low fat and highly digestible food) and perhaps some drugs to help control gut motility. However, if after the initial treatment the patient is still not responding, additional tests may be required, which might include;

  • Faecal examination – there are numerous specific tests which can be performed, such as;
    • Faecal flotation – check for parasites, worm eggs etc
    • Wet mount preparations – this technique will help you rule out other parasites such as Tritrichomonas foetus and Giardia
    • Stained faecal cytology – look for neutrophils, eosinophils, fungal and bacterial organisms
    • Faecal PCR, ELISA or IFA – check your external laboratory for available tests
  • Imaging studies - e.g. ultrasonography and radiography with barium
  • Endoscopy or surgery – colonoscopy is indicated to visually check the mucosal surface of the colon. This is an opportunity to collect biopsy samples
  • Further blood tests - check for FeLV, FIV and hyperthyroidism

Treating feline colitis – 5 ways forward

1. Diet

In many situations, a cat with diarrhoea can be helped by a simple change of diet. As many as half of all non-specific causes of feline diarrhoea will respond to diet alone.  Some of the typical food-responsive diarrhoea cases include;

  • Dietary allergies – these result from a reaction with a protein antigen (e.g. beef, wheat and corn)
  • Dietary intolerance – these are in response to an ingredient in the diet (e.g. colouring, flavouring)

The choice of diet is important. In the ideal world, avoid home-made and over the counter diets as these are inconsistent and confuse the diagnosis. If you think that the colitis is caused by diet, it’s best to suggest prescription diets as the formula and recipes are stable.

  • Veterinary diets – these offer the best dietary treatment. They will only contain the novel protein source you select. 
  • Hydrolysed diets – these are single-protein sources (usually soy, rice, or potato-based) which have undergone pre-digestion. They contain low-molecular-weight protein derivatives that are highly digestible and with low antigenic potential.
  • Prebiotic diets – these are diets containing fibres such as fructooligosaccharides. They are useful for colonic disease as fermentation products help mucosal function and modify enteric organisms, promoting "good" bacteria and inhibiting certain pathogenic bacteria. Did you know that all our feline diets contain prebiotics?

2. Probiotics

LactobacillusEnterococcusStreptococcus and Bifidobacterium are used to provide a beneficial effect on the gut microflora and are worth considering. Whilst the mechanism remains poorly understood, some probiotic strains are thought to be able improve the immune system. Read or article on Probiotics >

3. Antibiotics and anthelmintics

If the patient fails to improve, then you may consider a short trial therapy using an anthelmintic, food trial or perhaps antibiotics.

  • Worming treatments – this is often an early pharmacological treatment for colitis and might involve the use of fenbendazole (50 mg/kg/day) for 3 days. This can be repeated after 3 weeks if there is some improvement. Even if no worms or worm eggs are seen on faecal examination, this treatment is worth offering. 
  • Metronidazole – this is also frequently used in chronic colitis in cats. It has both antiprotozoal and antimicrobial activity and can even suppress some aspects of cell-mediated immunity. Although it is generally well tolerated, in high doses it can cause some reversible neurological problems, such as ataxia and nystagmus.
  • Tylosin – this is well tolerated in cats and produces few side effects. It’s effective against anaerobic gram-positive bacteria and some gram-negative bacteria. Since the speculative use of antibiotics is not recommended or appropriate these days, it’s always better to culture a faecal sample and test for the most effective antibiotic based on sensitivity results. Typically, Tylosin is usually ineffective against E.coli and Salmonella

4. Glucocorticoids

Cats presenting with chronic colitis are frequently treated with a combination of dietary management, metronidazole and glucocorticoids. Fortunately cats usually tolerate glucocorticoids very well.

Inflammatory changes in the colon are usually lymphocytic-plasmacytic, though other forms occur such as eosinophilic, neutrophilic, and granulomatous enteritis. The inflammation can be confined to the colon (colitis), though if it also involves the small intestine, it’s usually referred to as inflammatory bowel disease.

5. Immunotherapy

Immunosuppressive drugs tend to be used in combination with glucocorticoids when the response to steroids alone is not completely effective. The most commonly used drugs are;

  • Cyclosporine – used once daily (Atopica).
  • Chlorambucil – dose three times a week with prednisolone

What is the prognosis for colitis?

In the short-term, the prognosis for chronic feline colitis is usually good, though many cats will have relapses. Long term treatment is often required, but fortunately this can often be achieved with diet alone.