Chronic cases of diarrhea in cats are a familiar headache for many veterinarians. Symptoms can wax and wane over a period of time, which can complicate the veterinarians assessment of the response to treatment in some cases. Many, though not all of these cats, will have inflammatory bowel disease (IDB). This article will focus on how a veterinarian is able to diagnose IBD, and what the treatment options are.

There are many possible underlying causes when a cat presents with vomiting, diarrhea or weight loss:

1. Parasites (worms)

2. Viral disease (Coronavirus, Leukaemia virus)

3. Bacteria (Salmonella, Campylobacter)

4. Protozoa (Giardia, Tritrichomonas)

5. Dietary (food intolerance, food allergy)

6. Cancer (lymphoma, adenocarcinoma)

7. Inflammatory bowel disease

8. Hormonal or metabolic (hyperthyroidism, kidney failure)

9. Drug or toxin induced

10. Motility disorders

The veterinarian should take a full history from the owner, to avoid spending time and money on unnecessary testing. Factors to be considered are age, diet, appetite, worming history, weight change and the nature of the vomiting or diarrhea. It is important to differentiate vomiting from regurgitation, which is usually an esophageal problem, and to differentiate small intestinal diarrhea from large intestinal diarrhea by the frequency and consistency of the feces.

The veterinarian will then carry out a full clinical examination, before embarking on a basic approach to the diagnosis as follows:

1. Blood and urine tests to rule out disease elsewhere in the body which has a knock on effect on the gastrointestinal tract.

2. Bacterial culture of the feces to rule out Salmonella & Campylobacter

3. Parasite check on the feces to rule out worms

4. Xrays to rule out an obstruction by a foreign body or a tumor

5. Ultrasound examination of the abdomen to measure gut wall thickness

6. Bland prescription diet for 4-6 weeks (e.g. Hills Z/D, Royal Canin Sensitivity Control)

7. Intestinal biopsies via endoscopy or surgery.

IBD is a diagnosis of exclusion, so all of the differentials previously mentioned must be ruled out in order to make the diagnosis.

What is inflammatory bowel disease?

IBD is a term used to describe the inflammation of one of the layers in the intestinal wall. This swelling of the gut wall may occur with many other intestinal diseases, but when no cause of the inflammation is found after doing thorough testing as described above, the condition is described as idiopathic IBD (essentially, IBD of unknown cause). IBD is thought to be an overreaction to bacteria or dietary ingredients within the gut.

Are certain types of cats affected more than others?

Any age of cat can be affected, and pedigree breeds may be more commonly affected than domestic shorthair cats.

What are the treatment options once IBD has been diagnosed?

DIET

Many cats can be managed by diet alone in the long term. Diets can be hypoallergenic, high fiber or low residue. Sometimes all three of these types of food need to be trialed before the most effective one is selected. Cats are often resistant to dietary trials, and this is the main reason why many cats are given drugs to treat their IBD, the cat will just not eat the specific diet.

Hypoallergenic foods usually contain a new protein source that the cat has not encountered before such as capelin & tapioca, duck, venison or hydrolyzed protein. Diets high in fiber are recommended for colonic disease.

DRUGS

Drugs are a last resort, if the cat is still showing symptoms despite various food trials or if the cat refuses to eat the prescription diet.

Options are:

1. Anti inflammatory or immunosuppressive drugs

Prednisolone, a corticosteroid given at 2-4mg/kg, is the most effective drug.

2. Budesonide

This is also a steroid, with fewer side effects on the rest of the body but it is unlicensed.

3. Chlorambucil

Sometimes given in addition to a steroid if the steroid alone working.

4. Metronidazole

This reduces the number of bacteria in the gut, so theoretically will reduce the triggering factor for the inflammation.

5. Cyclosporine

Normally used in dogs, this modifies the immune system. It has only been tried in a small number of cats, with mixed results.