Pet Factsheets

Inflammatory bowel disease

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Inflammatory bowel disease (IBD) is a broad term for conditions that cause the lining of the digestive tract to become thickened and inflamed. Signs include chronic, intermittent vomiting and/or diarrhoea, weight loss, and anorexia (appetite loss).

Conclusive diagnosis of IBD requires biopsies (tissue samples) of the intestinal tract. Some vets may recommend a diet trial to test for food allergies. Many pets with IBD require a special diet as well as medication. The exact cause of IBD is unknown, and there is usually no cure, but it can frequently be controlled.

What is inflammatory bowel disease?

Inflammatory bowel disease (IBD) is a general term for conditions that cause the lining of the intestines to become thickened and inflamed. When this occurs, the digestive tract cannot absorb nutrients and move food substances properly. The entire length of the intestines may be involved, or just certain portions of the digestive tract may be affected.

What are the signs of IBD?

Cats with IBD can appear normal but may experience intermittent, but chronic, vomiting or diarrhoea. The signs may vary, depending on the portion of the digestive tract involved. Lesions at the beginning of the intestine may result in vomiting, while lesions further down the digestive tract may cause watery diarrhoea or diarrhoea with mucus or fresh blood. In more severe cases, the animal may lose weight, have loss of appetite, or have a thin, dull coat.

What causes IBD?

The exact cause of inflammatory bowel disease is unknown, but it is suspected that IBD is caused by chronic stimulation of the immune system from various factors, including dietary ingredients, parasites, or bacteria within the digestive tract. Genetics may also play a role.

How will my vet diagnose IBD?

Your vet will probably recommend a number of tests to rule out other causes of vomiting and diarrhoea, including faecal exams, blood tests, and radiographs (x-rays). An abdominal ultrasound may show thickened loops of bowel, which tends to occur with IBD. However, biospies (tissue samples) from the digestive tract are required for a definitive diagnosis of IBD.

Biopsies may be obtained during abdominal surgery, or via endoscopy using a fiberoptic endoscope (a long, narrow tube with a tiny camera at the tip). The endoscope can be inserted through the pet's mouth to reach the oesophagus, stomach, and small intestine, and/or inserted into the rectum to reach the large intestine. The instrument includes a small forceps, which the vet can guide, using the camera, to take tissue samples.

While both procedures require anaesthesia, endoscopy has the benefit of being less invasive, so the pet requires less time to recuperate. Endoscopy has some limitations, in that it may be difficult or impossible to reach some locations within the digestive tract, and only small samples may be obtained. For those reasons, surgery may be preferred.

Once a tissue sample is obtained, a specialist will examine the sample to determine the dominant type of cell found in the intestinal lining. This allows an exact diagnosis to be made, so treatment can be tailored to the specific type of IBD present.

What is a diet trial?

In some cases, your vet may suggest a hypoallergenic diet trial to rule out a dietary cause, such as an allergy. Although most pets with a food allergy develop problems with their skin (such as itching), some pets also develop signs consistent with IBD. In most cases of food allergy, the protein source in the food is usually the cause of the problem.

Before starting a diet trial, your vet needs a full history of what diets your pet has eaten in the past - include any human foods as well as any commercially prepared diets or treats. A diet trial usually involves feeding your pet a diet made using a protein source that your pet's immune system has not been exposed to before, such as venison, rabbit, fish, or duck. This means your vet needs to know what protein sources your pet has been eating, because those sources must be avoided for the duration of the diet trial. Another alternative is feeding a food that contains hydrolysed protein, meaning that the protein has been broken down into very small molecules so that the immune system won't recognise it.

During the trial, it is important that the pet eats only the hypoallergenic food and nothing else. All treats, edible chews (such as rawhide), and human foods must be discontinued. Feeding these items may expose the pet to the offending protein(s), which can confuse the results of the dietary trial. Typically, the animal is on the diet trial for a minimum of 12 to 16 weeks. If the signs improve or resolve during the trial and return when the pet is fed the previous diet, a diagnosis of food allergy can be assumed.

How is IBD treated?

Treatment of IBD varies depending on your pet's condition and the specific type of IBD determined by the biopsy. Most pets with IBD may require a special diet and/or anti-inflammatory or immunosuppressive medications. Other recommendations may include antivomiting and antidiarrhoea medications, antibiotics, parasite treatments, and/or probiotics.

Although IBD can't always be cured, it can frequently be controlled. Pets with IBD may have occasional relapses.