What is inflammatory bowel disease?
Inflammatory bowel disease (IBD) is a gastrointestinal (GI) disorder represented by an abnormal change to the lining of the GI tract.
This change results from the infiltration of inflammatory cells into the GI tract lining, interfering with the ability to absorb water and nutrients and causing inflammation, thus disrupting normal GI function. Depending on which portion of the GI tract is involved, the clinical signs of the disease will be different. If the stomach or the beginning portion of the small intestine (duodenum) is involved, the most common sign is vomiting. If the sections of the small intestines farther from the stomach (jejunum and ileum) are involved or if the disease affects the colon, diarrhea can be seen. In some cases of inflammatory bowel disease, the only clinical sign seen in the pet is weight loss.
How is inflammatory bowel disease diagnosed?
If your pet is showing any of the above mentioned signs, usually for longer than 3 weeks, it is possible that he or she has IBD. However, there are many other causes of vomiting, diarrhea and weight loss in the dog and cat. The first step is to collect a metabolic data base, including a complete blood count (CBC), a serum chemistry profile and urinalysis. Radiographs (x-rays) may also be taken of the abdomen to identify structural changes to the GI tract or other internal organs that can affect the GI tract and cause weight loss. It is also important to check the feces for parasites, as these too can cause vomiting or diarrhea. All of these diagnostic tests can be and are often normal in animals with IBD, but help to rule out potential causes of vomiting, diarrhea and weight loss.
If inflammatory bowel disease is suspected, we can try to treat symptomatically with medications or do further diagnostics to find a definitive diagnosis. The medications used reduce the urge to vomit, slow down the GI tract to relieve diarrhea, or reduce gastrointestinal inflammation. Also, deworming medication may be prescribed as some parasites are difficult to identify on routine fecal tests. If the symptomatic therapy does not relieve the diarrhea and/or vomiting, or if the signs return shortly after stopping the medications, the next diagnostic step is to obtain biopsies of the gastrointestinal tract either through endoscopy or surgical exploration of the abdomen.
Endoscopy is the visualization of the gastrointestinal tract through the use of an endoscope, a narrow, flexible tube with a light and camera at its end. Not only can we see the lining of the esophagus, stomach, small and large intestines with an endoscope, but because endoscopes have a working channel along their length, biopsy instruments can be advanced down the endoscope and small biopsies of abnormal tissue can be obtained. Animals are anesthetized for the procedure but recover quickly and can go home the same day.
Biopsy samples can also be obtained through surgery. The advantages of endoscopy over surgery are: 1) There are no incisions that need to heal with endoscopy. 2) With an endoscope, you can actually see the changes to the GI tract lining, allowing a more accurate sampling of the tissues. 3) The procedure takes less time, so the animal is under anesthesia for a shorter time. The advantage of surgery over endoscopy is that other tissues/organs in the abdomen can be seen and sampled if abnormal during the surgery.
Once obtained, the biopsy samples are sent to a pathologist, who can diagnose inflammatory bowel disease by the type of cells present. Other diseases, such as intestinal cancer and parasitism can also be identified.
How is inflammatory bowel disease treated?
The most common ways to treat IBD is through medication and diet. The medications are designed to suppress inflammation of the GI tract. Some of the more commonly used medications are prednisone, metronidazole, sulfasalazine and azathioprine. Typically these medications are tapered over a period of months once the inflammation and alteration of the GI tract has subsided.
The exact cause of inflammatory bowel disease is unknown, but it is believed that the changes to the gastrointestinal lining are due to a chronic stimulating irritant. One stimulus suspected is the protein in the animal's food. If the protein is causing an allergic response, then changing the food, or more specifically changing the protein in the food should remove this irritation. Foods containing a novel protein (protein the animal has never been exposed to) or protein that has been hydrolyzed (a process that breaks the protein into particles too small to be recognized) are often used in conjunction with medications.
There is no cure for inflammatory bowel disease, therefore treatment is life long. Once the disease is under control, there are often long periods of time where no signs of IBD are present, but flare-ups inevitably occur, requiring restarting or increasing the dosage of medications. Some cases of IBD can be maintained with dietary therapy alone, but most need some degree of medication to keep the disease under control.