Inflammatory Bowel Disease in Small Animals

by Julie Callahan, DVM, DACVIM

Inflammatory Bowel Disease, or IBD, is a complex disease process of the intestinal tract that is a common cause of chronic gastrointestinal (GI) upset in dogs and cats.  This inflammatory condition causes a combination of clinical signs including changes in appetite, vomiting, diarrhea, and weight loss.  The underlying cause of this disease is not completely understood but several contributing factors have been identified including breed predisposition, dietary intolerance, inappropriate reaction to the bacterial environment of the GI tract and immune system dysfunction.  The diagnosis of IBD involves ruling out other common causes of GI upset in small animals including GI parasites, Addison’s disease, pancreatic disease and other organ system diseases (i.e. kidney or liver disease).  These differential diagnoses form the basis of the diagnostic workup of patients with chronic GI disease, which includes: routine systemic health check (complete blood count, chemistry profile and urinalysis), fecal testing for infectious diseases, a screening test for Addison’s disease (cortisol or ACTH stimulation test) and GI/pancreatic markers of disease (Vitamin B12/folate, PLI/TLI). The ultimate diagnosis, however, is achieved with the aide of GI biopsies.  Biopsies can be obtained via surgery or by a minimally invasive approach using endoscopy.  Endoscopy involves inserting a camera into a patient’s GI tract (either through the mouth or the rectum) in order to obtain several small biopsy samples from the affected areas. Once a diagnosis is obtained, therapy can be pursued and tailored to each specific patient.  Therapy may consist of a diet (exclusively a prescription hypoallergenic diet), antibiotic medication, deworming medication and immunosuppressive therapy.  Depending on the severity of signs and disease (according to biopsies), treatment and prognosis can vary.  The following two cases will highlight the wide range of signs and responses seen with this disease.

Charlie Danley, a 5 year old male Doberman Pinscher, was initially presented to NEAMC for chronic vomiting, weight loss, lethargy and a more recent history of diarrhea.  Charlie had lost a whopping 25 pounds and was very thin when we first met. 

His lab work showed that he was not able to absorb nutrients from his food normally- his blood protein, cholesterol and his vitamin B12 level were all well below normal.  These changes indicate significant disease and renders such patients at increased risk for complications of GI disease (such as blood clot formation, poor healing and failure to maintain body weight). 

Charlie had seen multiple veterinarians who performed a full battery of diagnostic tests (including blood work, fecal testing, x-rays and abdominal ultrasound) and prescribed a variety of treatments, however Charlie never improved significantly.  Finally, Charlie saw Dr. Jean Pitcairn who recommended Charlie come to NEAMC for an upper gastrointestinal endoscopy with biopsies.  In some cases, especially those with severe disease, biopsy results become crucial- this is the only way that we can be certain what disease process is occurring and therefore know the most effective treatment to prescribe.  We performed the procedure the same day Charlie came to us as a consultation and he was able to be discharged that day.  Biopsies confirmed a diagnosis of moderate to severe IBD so Charlie was started on a combination of a hypoallergenic diet and immunosuppressive doses of a steroid medication (prednisone).  Over the first 2 weeks of treatment Charlie’s energy improved, he did not vomit but his diarrhea continued.  We added a second medication to suppress his immune system’s attack on his intestines and by the end of his first month of treatment he had gained over 4 pounds and his blood protein and cholesterol were normal.  Today, 2 & ½ months into treatment Charlie is doing fantastic!  He has gained almost 20 pounds and he has had a normal energy level, no vomiting and a few weeks of normal stool consistency! Charlie represents a case of severe IBD.  He was severely affected and required thorough diagnostic evaluation in order to determine how best to help him.  It took several weeks and multiple medications, but Charlie is in the 30% of dogs with protein losing GI disease who responds completely to medical therapy.  Other dogs may only partially respond and unfortunately, some dogs with disease as severe as Charlie’s don’t respond at all. 

Not all dogs (or cats) with GI disease are as severe as our friend Charlie.  We have also recently seen Grady, a young Shih-Tzu, in the clinic.  Grady was presented with a one year history of vomiting and diarrhea.  He was otherwise feeling great and was maintaining a healthy weight and appetite despite his GI signs.  Routine blood work and fecal test was normal indicating, in combination with a healthy weight, that there was not a significant component of malabsorption of nutrients.  In this case, extensive work-up was not required and we started by prescribing a hypoallergenic diet (my favorite diet is Royal Canin HP).  Within a few weeks, Grady was no longer vomiting and was continuing to feel great!  Food intolerance and dietary allergy are not uncommon in our small animal patients.  The most common allergens are chicken and beef, which are standard ingredients in our pet foods.  Fortunately, we have prescription diet options available that can successfully manage cases of food intolerance/allergy.  There are diets that are formulated with components that are easy to digest, those that contain novel protein sources (such as duck and rabbit) and those that are hydrolyzed (essentially means that the protein sources are pulverized to such a degree that the body can no longer recognize them as an allergen) that are available via a prescription.  Occasionally, an over the counter diet with a novel protein source can ameliorate clinical signs, however it is important to be aware that there is a lack of oversight of such diets and claims made by these companies may not be accurate (and therefore the diet may not work).  When performing a diet trial, it is very important to be strict and exclusively feed the prescription diet for at least 2 consecutive weeks with no other treats or supplements (including flavored heartworm preventatives).  If there is food intolerance or allergy, clinical improvement should be noted within those 2 weeks.  If a patient does not respond, further work-up, likely consisting of endoscopy with biopsies would be recommended.

GI disease is one of the most common presentations at NEAMC.  If your dog or cat frequently vomits, has chronic intermittent diarrhea and/or weight loss we may be able to help, so please don’t hesitate to schedule a consultation. 

After: Charlie loving life after treatment and gaining 20 pounds!