Lymphocytic Plasmacytic Gastroenteritis in Cats

By Courtney Barnes, BSc, DVM; Malcolm Weir, DVM, MSc, MPH; Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP

What is lymphocytic plasmacytic gastroenteritis?

Lymphocytic plasmacytic gastroenteritis is a form of inflammatory bowel disease. Inflammatory cells infiltrate the lining of the stomach and intestine as the result of an abnormal immune response.

While the exact cause is unknown, it is possible that intestinal bacteria may be involved in stimulating the immune response. That is, the body reacts to the intestinal bacteria as though they were foreign, releasing cells that cause inflammation. Environmental, dietary, and immune-system factors also likely play a role in disease development.

While most cats with lymphocytic plasmacytic gastroenteritis are middle-aged, this disease has been diagnosed in cats as young as 5 months. The signs and symptoms vary in intensity and frequency, but generally, cats exhibit signs of disease intermittently at first, with the frequency of episodes increasing over time.

What are the signs of lymphocytic plasmacytic gastroenteritis?

Diarrhea is the most common symptom in most cats, but vomiting occurs when the stomach is most affected. Other possible signs include loss of appetite, long-term weight loss, blood in the stool and/or vomiting. Severe protein loss is uncommon in cats but if it occurs, signs of ascites (fluid in the abdomen) or edema (fluid in the subcutaneous tissues) may be present. Abdominal pain may be present.

What other conditions can look like lymphocytic plasmacytic gastroenteritis?

Several conditions have signs like lymphocytic plasmacytic gastroenteritis, including granulomatous inflammatory bowel disease, lymphangiectasia, gastrointestinal infections (e.g., histoplasmosis, Salmonella, Giardia, and bacterial overgrowth), gastrointestinal cancers, and pancreatic disease.

What tests are used to diagnose lymphocytic plasmacytic gastroenteritis?

A complete blood count and blood chemistry panel are often normal in these cats, although the cat may have mild anemia (low red blood cell count) or low protein levels. Tests for pancreatic disease may be recommended to rule out pancreatitis or a problem with pancreatic function (exocrine pancreatic insufficiency). Levels of vitamin B12 (cobalamin) and folate may also be measured to assess the ability of the intestines to absorb nutrients. Plain abdominal X-rays (radiographs) typically look normal, but barium X-rays may reveal thickened loops of bowel. An abdominal ultrasound will likely be recommended and may be more diagnostic than X-rays, as it allows bowel wall thickness to be more accurately measured.

Your veterinarian may recommend a hypoallergenic diet trial to rule out a nutritional intolerance, such as an immune reaction to a specific protein. Some forms of immune-mediated gastrointestinal disease in cats may respond to changes in diet, in which case, the diagnostic plan is complete. Independent of the path to a diagnosis, most cases of lymphocytic plasmacytic gastroenteritis are helped when nutrition is part of long-term management.

"Your veterinarian may recommend a hypoallergenic diet trial to rule out a nutritional intolerance, such as an immune reaction to a specific protein."

The definitive diagnosis of lymphocytic plasmacytic gastroenteritis involves a biopsy that is evaluated by a pathologist. Most often, the biopsy is taken via the less invasive technique of endoscopy, rather than by an open-abdomen surgical procedure.

Some cats may have concurrent pancreatitis and cholangiohepatitis, a condition termed “triaditis”. These cats will be more severely ill. The condition is diagnosed based on  elevated liver enzymes and pancreatic lipase immunoreactivity (PLI) testing. It is unknown whether small cell lymphoma (the most common gastrointestinal cancer in cats) is a progression of severe inflammatory bowel disease or is a separate condition.

How is lymphocytic plasmacytic gastroenteritis treated, aside from managing nutrition?

If there is any dehydration, inappetence, or ongoing vomiting, the cat may need to be admitted to the hospital for anti-nausea medication, pain medication, appetite stimulants, and IV fluid therapy. Immunosuppressive medications are used to control the symptoms of lymphocytic plasmacytic gastroenteritis. Prednisolone is the most prescribed medication, but other corticosteroids and immunosuppressive medications may be tried. Once the cat feels better, the immunosuppressive therapy can be tapered down to the lowest dose that keeps the cat’s symptoms under control.

Other treatments can include antibiotic therapy and cobalamin (B12) supplementation, as well as prebiotics and probiotics to help improve gut bacterial flora.

What kind of follow-up will be needed once my cat’s symptoms are under control? Will she ever be normal again?

Cats with severe clinical signs require more frequent monitoring. The end point of treatment is the resolution of clinical signs. Most cats are monitored every two to three weeks initially, and then every month or two until the immunosuppressive medications can be withdrawn. Cats with a mild case of lymphocytic plasmacytic gastroenteritis have an excellent prognosis. Those with a more severe case have a more guarded prognosis. Some patients may need to remain on immunosuppressive drugs for the rest of their lives.

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