Inflammatory bowel disease is a syndrome of chronic inflammation and irritation in a cat's gastrointestinal tract, which includes the mouth, esophagus, stomach, small intestine, and colon (large intestine). The most common symptom is chronic vomiting, but in some cats, chronic diarrhea, or both vomiting and diarrhea, occur. It can also cause weight loss, lack of appetite, and lethargy.
Middle-aged to senior cats are likeliest to develop inflammatory bowel disease, although it can occasionally strike younger cats. The syndrome is not always easy to diagnose, and it has complex causes that are not fully understood, but with treatment, which generally includes both medications and diet modifications, your cat can have a good quality of life.
What Is Inflammatory Bowel Disease?
Inflammatory bowel disease (IBD) is a gastrointestinal syndrome where the GI tract is chronically inflamed and irritated. It occurs in many animals, including dogs and humans. The cause of this disorder is not well understood, but it is likely due to abnormal interactions between the immune system, dietary factors, bacteria in the intestines, and possibly genetics.
The chronic inflammation of the GI tract leads to thickening of the walls of the cat's digestive system organs, which makes it more difficult for them to perform their functions of digesting food and absorbing nutrients.
IBD is a complex condition, and takes many forms. If it predominantly affects the cat's stomach, it is called gastritis. If the inflammation is mostly in the large intestines, the condition is labeled colitis. However, most often it is the small intestines that have the worst inflammation, and this type of IBD is called enteritis. Note that a cat may have inflammation in all areas of the GI tract, however.
Occasionally, the cat's liver and/or pancreas are also inflamed.
Symptoms of IBD in Cats
As IBD is a gastrointestinal disease, the most common symptoms are general GI signs. This can be vomiting, diarrhea (with or without blood), a lack of appetite, weight loss, and/or lethargy. If the cat mostly experiences vomiting, many owners dismiss the symptom as nothing more than hairballs or mild stomach upset. However, it is not normal for a cat to experience frequent vomiting. In fact, if your cat vomits more than once a month, that's an indication that there may be an underlying health problem of some type that requires a visit to the veterinarian.
If your cat has IBD, they may have any combination of these symptoms, or they may only have one symptom, typically chronic vomiting. The symptoms your cat shows will also depend on what part of your cat's GI tract is inflamed. If it's the stomach with the worst inflammation, vomiting is the chief symptom. Severe inflammation of the intestines leads to chronic diarrhea. If the cat has inflammation throughout the entire GI tract, it may experience both chronic diarrhea and vomiting. Symptoms can come and go and vary in severity.
As the inflammation slowly thickens the walls of the GI tract, impairing its function, it's common for your cat to lose weight, become lethargic, lose interest in eating, and sometimes develop a straggly or ungroomed-looking coat. Some cats, conversely, become hungrier than normal, due to the underlying malnutrition caused by the IBD.
Causes of Inflammatory Bowel Disease
The symptoms of IBD are caused by chronic inflammation within the cat's GI tract, but that inflammation is triggered by one or more underlying issues. Because IBD in dogs and humans has a known relationship to genetic abnormalities in the immune system, it is assumed that the same is true of IBD in cats. Other suspected triggers include bacterial infections of the GI tract, infestation with intestinal parasites, and food allergies to various proteins. Often, the underlying cause cannot be determined, however.
Diagnosing IBD in Cats
Since the symptoms (or symptom) of IBD are also symptoms of other gastrointestinal illnesses, your vet may want to run a variety of tests to rule out other issues.
Along with a full physical exam, your veterinarian will likely order a variety of blood tests to assess your cat's overall health, including kidney, liver, and thyroid function. A complete blood count can indicate anemia, infection, or allergies, depending on the number and type of white blood cells. Occasionally, your vet might want to test the cat's blood levels of vitamin B12, as decreased levels indicate gastrointestinal difficulty with absorbing nutrients. Often, blood folate levels are checked at the same time, as high levels can indicate an overgrowth of bacteria in the intestines, while low levels indicate intestinal disease.
When you call to make your appointment you will probably be asked to bring in a fresh stool sample so your vet can check for intestinal parasites. Try to collect your cat's stool the day of the appointment for the most accurate results.
An abdominal ultrasound is a common component of a workup for a cat suspected of having IBD, as it can show the characteristic thickening of the intestinal walls and stomach and may also rule out cancer or pancreatitis.
For a definitive diagnosis of IBD, your vet will need to take biopsies of your cat's GI tract. These samples are then sent off to a veterinary pathologist, who will look at the samples microscopically to detect inflammatory changes that are typical with inflammatory bowel disease.
Treatment & Prevention
Since IBD can sometimes be caused by food allergies, your vet may recommend a special diet for your cat. This could be a commercially prepared, 'limited ingredient' diet or it could be a prescription, hydrolyzed diet.
If choosing a commercial diet, it is important to pick one that uses a novel protein. This means selecting a protein source that your cat has never eaten before. Most commercial limited ingredient cat diets utilize rabbit, duck, or venison as their protein.
Prescription diets contain proteins that are hydrolyzed, meaning they are broken down into their individual amino acid components so that your cat's immune system will not recognize them as a potential allergen.
Whether you start your cat on a commercial diet or a prescription type, it is vitally important that you only feed the new diet for a period of 8 to 12 weeks. This means no other food, treats, etc. as these may cause a potential adverse reaction, making you believe the new diet isn't working.
Your vet may also start your cat on the antibiotic metronidazole to help treat any bacteria that may be causing the IBD symptoms. Corticosteroids such as prednisolone will work to suppress your cat's immune system so that it doesn't overreact to an allergen or something potentially inflammatory. However, long term steroid use in cats comes with its own set of concerns, so your vet will instruct you on how to taper the dosage so that you are giving as minimal amount as possible while still providing relief.
Because the causes of IBD are often unknown, and so are difficult to predict or control, there is little you can do to prevent your cat from developing inflammatory bowel disease other than feeding it a high quality diet, visiting your vet regularly for checkups, and taking lengthy or frequent bouts of diarrhea or vomiting seriously.
Prognosis for Cats with IBD
IBD can be treated, but not cured. Still, with proper treatment, most cats improve and lead happy and normal lives, although occasional flareups of the condition are common. If your cat does well on its special diet, that diet should be continued for the remainder of the cat's life. It's also a good sign when the cat responds well to medical management of the IBD.
If your cat does not respond to dietary changes or medications, however, the prognosis is not as good. In these cats, further testing may be recommended, as intestinal lymphoma, which is a type of cancer, may have developed.
Inflammatory Bowel Disease in Cats. VCA Animal Hospitals.
The Symptoms of Inflammatory Bowel Disease (IBD) in Cats. NortheastVeterinary Referral Hospital.
Inflammatory Bowel Disease. Cornell University Feline Health Center.
Frequent Vomiting in Cats: Signs, Causes, and Treatment. River Landings Animal Clinic.