Inflammatory Bowel Disease

38-inflamatory-bowel-disease2-300x199Inflammatory Bowel Disease (IBD) is characterized in dogs by chronic intermittent vomiting, diarrhea and weight loss and in cats by anorexia (decreased appetite), weight loss, vomiting and/or diarrhea.  Though the cause is not known, this condition appears to be immune-mediated.  The presence of increased numbers of inflammatory cells within the stomach and intestinal wall may be responsible for the interruption of normal bowel function.  The cause of IBD is most likely multifactorial and involves complex interactions between genetics, immunity, and environmental (GI flora) factors.Treatments may include hypoallergenic diets, antibiotics, probiotics, and corticosteroid therapies.  Blood chemistry profiles are used to rule out other disease processes that may mimic IBD, and an intestinal wall biopsy is performed to confirm inflammatory cell presence and rule out neoplasia (cancer).

The inflammatory cells associated with Inflammatory Bowel Disease include lymphocytes, plasmacytes, eosinophils, and neutrophils.  These are white blood cells that produce antibodies and histamine, as well as phagocytize or consume bacteria.  The predominance of one or more cell type determines the type of IBD, but this does not change the course of treatment.

On examination, an animal with IBD may appear thin due to malabsorption of nutrients and protein loss through the chronically irritated gut wall.  Upon abdominal palpation, the intestines may feel “ropey” or thickened.  Thickening of the intestinal wall causes a reduction in peristalsis, the normal contractions that move stool through the GI tract.  Stools may contain mucous and or blood.  Cats may stop grooming themselves or may over-groom the perianal area.  In some patients, vomiting and diarrhea may be the only obvious symptoms.

Blood chemistry results are often within normal limits in the IBD patient.  Liver and pancreatic enzymes may be slightly elevated.  Plasma albumin and potassium may be decreased.  There is no blood test for inflammatory bowel disease; however, ruling out other disease is necessary to make a proper diagnosis.

Fecal exams and cytologies are performed to rule out parasites and infections such as whipworms, giardia, and clostridial overgrowth.

X-rays and abdominal ultrasound may show thickened loops of intestine, but this finding in itself is not a confirmation of the disease.  Radiography is instead used to help eliminate tumors as a cause of symptoms.

Biopsy by endoscopy or exploratory laparotomy is the only definitive way to confirm the presence of inflammatory cells within the stomach and intestinal wall.  A general anesthetic is administered to facilitate tissue collection.  An endoscope is a narrow tube with a camera and forceps attached at the end that is passed through the esophagus to obtain upper GI tissue biopsies, or through the colon to harvest lower GI tissue samples.  It is not always possible to collect diagnostic samples using an endoscope.  So exploratory laparotomy, though obviously more invasive, is sometimes necessary.  After surgery, the tissue samples are sent to a pathologist for examination.

Some patients will improve during a food trial with a prescription hypoallergenic diet.  There are two basic types of food available by prescription for IBD: novel protein, novel carbohydrate formulas and hydrolyzed protein formulas.  Whichever type of food is used, the most important factor in realizing their effectiveness is to eliminate all other sources of calories.  This includes treats, table scraps, rawhides, even flavor-infused chew toys as they all may contain ingredients to which the pet is allergic.

Oral medications are used to treat patients who do not respond to food trials.  These include antibiotics, anti-emetics, and corticosteroids, often prescribed in combination with each other.  Because there is no cure for Inflammatory Bowel Disease, long-term use of these drugs is used to control symptoms.  There are possible side effects from chronic steroid use, so your veterinarian will usually prescribe a tapering dose regimen to determine the minimum dose required to alleviate symptoms.  Prednisone (prednisolone) is the steroid of choice, although a safer drug called budesonide, which is less systemically bioavailable, may control some IBD patients.  Steroids should only be used in patients suspected of having intestinal lymphoma (an intestinal cancer) after definitive diagnosis with intestinal biopsies.  Antibiotics used include metronidazole, sulfasalazine, and tylosin.  These drugs are used for their anti-inflammatory effect as well as to normalize the bacterial flora in the gut.  It is important to use a therapeutic dose of antibiotic so that bacterial resistance is less likely.  Sulfasalazine is used on a short term basis because of a risk of KCS (reduced tear production), and it may be toxic to cats because of its aspirin content.  Anti-emetics are medications that control vomiting.  Metoclopramide is an antiemetic that also increases peristaltic contractions, making it a good choice for IBD treatment.

While not considered a drug, probiotics may be useful and improve symptoms of Inflammatory Bowel Disease.  Probiotics are live forms of beneficial bacteria that normally reside in the healthy intestine.  In-vitro studies show that it may have anti-inflammatory effects by blocking the enzymes produced by white blood cells in the gut wall.  The most common probiotics typically administered to dogs are Lactobacillus, Bifidobacterium, and Enterococcus.  They are available over the counter as well as in pet products specifically made for the treatment of diarrhea.

It should also be noted that Omega 3 fatty acid supplements may be of benefit in the IBD patient.