Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome (IBS)

By: Dr. Erika de Papp

Section: Veterinary Care In-depth

Diagnosis In-depth

  • A history and physical exam are necessary to guide the diagnostic work-up. Careful history taking should help determine if the clinical signs are consistent with the classical presentation of animals with IBS. Physical exam findings of animals with IBS are usually unremarkable. Abnormalities found on the physical exam may be more suggestive of another disease entity.

  • Complete blood count. The CBC evaluates the red and white blood cells as well as the platelets. The CBC is usually normal in these patients, but it may be helpful to rule out other disease processes that may cause signs similar to IBS.

  • Biochemical profile. The biochemical profile helps to evaluate liver and kidney function as well as assessing blood sugar, protein and electrolyte levels (sodium and potassium are examples of electrolytes). This is imperative in ruling out diseases of other body systems such as liver and kidney disease.


  • Urinalysis. Evaluation of the urine together with the biochemical profile is necessary to fully assess kidney function.

  • Fecal tests. Fecal analysis is necessary to diagnose bacterial and parasitic infections. A fecal float looks for worm eggs. A fecal culture is necessary to rule out the bacterial causes of infection, and there is a specific fecal test to diagnose Giardia.

  • Fecal cytology. This involves examining the feces under a microscope to look for evidence of inflammatory cells, which may be indicative of an infectious process or another disease such as IBD. Fecal cytology should be normal in patients with IBS.

  • Bacterial overgrowth can be assessed in several ways. One method involves getting samples of intestinal juice and culturing it to evaluate the total number of bacteria present. Bacterial overgrowth can also be implied by measuring blood levels of cobalamin (Vitamin B12) and folate. Cobalamin is often consumed by bacteria and folate is a substance produced by bacteria. Therefore, alterations in the levels of these two substances can be suggestive of bacterial overgrowth.

  • Food trial. Switching the animal's food to a new diet or a hypoallergenic diet may indicate an allergy to a specific food if the signs resolve following cessation of the previous diet.

  • Abdominal ultrasound. Ultrasound exam of the abdomen may help pinpoint the site of the problem. Animals with IBS have normal exams. Evidence of intestinal thickening or enlarged lymph nodes or tumors in the abdomen will help exclude a diagnosis of IBS.

  • Intestinal biopsy. Biopsy of the intestine is necessary to rule out inflammatory and cancerous causes of the clinical signs. This is often done via endoscopy, which is a scope placed into the animal's intestinal tract either via the mouth or the rectum. Biopsies of the stomach as well as the small and large intestine can be obtained by this method.

    Therapy In-depth

    Treatment principles for IBS involve manipulating the diet to create a highly digestible food source. Additionally, many animals respond favorably to addition of fiber to the diet. Fiber is thought to normalize gastrointestinal motility. Many animals will not respond to dietary therapy alone and may require anti-diarrheal, anti-spasmodic, anti-gas and even tranquilizing drugs during episodes of marked discomfort.

  • Dietary modification. A diet that is low in fat and highly digestible is recommended. This should be a diet that the pet has never eaten before. Hypoallergenic diets may also be used. Fiber can either be added to the diet, or high fiber formulations may be prescribed. It is important to note that each animal is different with respect to their response to a particular diet and the dietary modification must be tailored to the individual.

  • Antidiarrheal drugs. Loperamide (Imodium) and diphenoxylate (Lomotil) are drugs that may be useful in dogs whose predominant signs are diarrhea and urgency to defecate. They work by decreasing intestinal secretions, promoting absorption, and altering intestinal motility. They should be used under the supervision of your veterinarian, as some dogs may have worsening of bloating and abdominal discomfort as a side effect.

  • Antispasmodic/tranquilizer medications. Librax is one example of a combination drug that may alleviate discomfort associated with bloating. It contains a Valium-type sedative and an antispasmodic agent that reduces intestinal motility. This type of drug is generally used on a short-term basis only.

  • Anti-gas drugs. Over the counter medications such as Gas-X and Mylanta-Gas contain a drug called simethicone, which alleviates intestinal gas. This is another drug that should only be used after consulting with your veterinarian.

     
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