Inflammatory Bowel Disease (IBD) in Dogs and CatsJanuary 18, 2023
What is IBD?
Inflammatory bowel disease (IBD) is one of the most common causes of chronic gastrointestinal symptoms in dogs and cats. It can be diagnosed in any age group, but is most commonly seen in young adult to middle-aged adult dogs or cats. Any breed can be affected but there is a known genetic component in Siamese cats, German Shepherd dogs, Basenjis, Soft-Coated Wheaten Terriers, and Chinese Shar Peis.
IBD is sometimes confused with irritable bowel syndrome (IBS). IBS is a separate condition with a different treatment plan.
Symptoms of IBD in dogs & cats
Dogs and cats with IBD will exhibit one or more clinical signs such as:
- weight loss
- decreased appetite
Some dogs and cats will continue to feel well other than vomiting and/or diarrhea and will act normally and engage in their normal routine. Other pets will feel sick even in between episodes of vomiting/diarrhea. They may not eat well, are lethargic, and do not want to participate in their normal routine.
Causes of IBD
The cause(s) of IBD is not clearly understood. The most commonly held theory involves a breakdown of the immune function specific to the gastrointestinal tract (GIT). The immune system must be very sophisticated and know that it does not need to react to normal bacteria and food particles that traverse the GIT. In pets with IBD, this tolerance is lost.
An abnormal immune response is initiated and creates inflammation within the layers of the intestine. The intestine is negatively affected and can no longer do its normal jobs. This results in the clinical signs as described above.
Triggers of this abnormal immune response include genetics, environmental, dietary, and microbial (bacteria, etc.) factors.
Diagnosing IBD in your pet
Diagnosing IBD can begin with your pet’s primary care veterinarian, but you may need to consult with an Internal Medicine Specialist.
A pet with chronic GIT symptoms will undergo a variety of tests to identify other causes of vomiting/diarrhea, weight loss, and decreased appetite. Testing will include a “minimum data base” which includes a complete blood count, chemistry panel, and a urinalysis. The combination of tests will exclude a variety of conditions such as liver disease, kidney disease, among others. Endocrine testing may also be performed such as a thyroid level in cats and a cortisol level in dogs to exclude hyperthyroidism and hypoadrenocorticism (Addison’s disease), respectively. Pancreatic function may be tested with specialized blood tests. The stool will be tested in pets that are exhibiting chronic diarrhea. Broad spectrum deworming may also be recommended.
An abdominal ultrasound will be recommended to look for structural changes to the GIT or other organs, that may prompt additional testing.
Ultimately, a diagnosis of IBD is achieved with biopsies of the GIT. The goal of biopsy is to detect the presence of inflammation, determine if microscopic structural changes are present, and to look for cancer or fungal infections.
There are two ways to obtain biopsies – endoscopy and surgery. There are advantages and disadvantages to both. Advantages of endoscopy are its ability to obtain multiple biopsies of the stomach and intestinal lining and it allows visual inspection of the stomach and intestinal lining. However, endoscopy is only able to collect tissue from one layer of the GIT (mucosa). Surgery collects full thickness biopsies which allows analysis of all the layers of the GIT, but is more invasive and has a longer recovery period.
How is IBD treated?
About 30% of dogs with IBD will be dietary responsive. Possible treatments for IBD include a strict diet trial with a novel protein (venison, rabbit, duck) or hydrolyzed diet (the proteins are broken down into small peptides that do not activate the immune system). During a diet trial, your pet cannot receive any other proteins – no other treats, flavored medications (such as heartworm flea/tick preventative,) rawhide, or other animal-based chew products. If your pet is used to receiving treats, kibble can be given in their place. Alternatively, making treats with canned food can be done too. Symptoms would be expected to improve within the first two weeks of exclusive feeding but may take as long as 4 weeks.
Pets with IBD associated diarrhea may also be antibiotic responsive. Diarrhea that responds to treatment with metronidazole or tylosin may resolve completely. If the diarrhea returns after completion of the antibiotic course, long-term treatment with tylosin may be considered for control of the IBD.
Some pets with IBD do not respond to diet changes or antibiotics and they require immune suppression to control clinical signs. Immune suppression is achieved using a steroid (prednisone, prednisolone, or budesonide) along with a novel protein or hydrolyzed diet regimen. The medication is slowly tapered over months to achieve the lowest effective dose. Immune suppression may be stopped in time and control the IBD is maintained with strict diet control. Some pets are refractory to steroids and additional medications must be added.
Ideally, steroids are started after a solid diagnosis of IBD is made via biopsy. However, if biopsy is not possible then a prednisone treatment trial can be considered. Prednisone is inexpensive and may control the current symptoms. If prednisone does not control the clinical signs, the pet may not have IBD or has refractory IBD that requires additional immune suppressing medication. Interpretation of intestinal biopsies after being treated with prednisone or other medications are more difficult to interpret due to microscopic alteration of the tissue.
Inflammatory bowel disease carries an overall good prognosis with management. However, a small subset of pets will have persistent symptoms despite appropriate treatment.
If your cat or dog is having episodes of vomiting or diarrhea more than once a week, a visit with your pet’s primary care veterinarian is recommended.