Page 776 - Problem-Based Feline Medicine

768 PART 9 CAT WITH SIGNS OF GASTROINTESTINAL TRACT DISEASE

due to food allergy and that due to other causes. Cats A diagnosis of colonic IBD is based on exclusion of
with food allergy usually have signs that resolve within all other causes of colitis in conjunction with the histo-
4 days on an appropriate hypoallergenic diet. Signs of logic presence of an increased number of inflamma-
IBD do not usually resolve solely with a change in diet, tory cells in the lamina of the crypts.
although they may improve.
The histopathologic changes associated with colonic
IBD are quite variable and include infiltration of the
Treatment lamina with lymphocytes and plasma cells (most
common), eosinophils, macrophages, neutrophils, or
Food allergy is diagnosed and treated by feeding an
a combination of these cells.
elimination diet for the dietary trial period.
An immunologic mechanism is suspected primarily
Homemade diets allow the use of a single novel
because of the response to immunosuppressive therapy,
protein source (turkey, duck, venison, etc.) and a
but this has not been proven.
novel, highly digestible carbohydrate source (rice,
potato) without preservatives, flavorings, or other The disease in cats is so heterogeneous (compared to
additives that may be cause of the problem. human IBD) that it likely represents a combination of
Alternatively, use a commercial hypoallergenic diet genetic (purebred cats have a higher incidence), envi-
containing protein and carbohydrate the cat has been ronmental, infectious (bacterial), dietary and
previously exposed to. immunologic components.

However, homemade diets are not recommended for
long-term management of food allergy as they are not Clinical signs
balanced or nutritionally complete.
Hematochezia is the most commonly observed clinical
There are a number of commercial diets that have sign in colonic IBD.
been formulated as “hypoallergenic” or limited
When large bowel diarrhea occurs, it may be either mild
antigen diets. Many of these diets (Hill’s, Innovative
and intermittent or persistent and severe in character.
Veterinary Diets, Royal Canin, Iams, Nature’s Recipe,
Nutro, and Wysong to name just a few) will be quite Most cats with the colonic form of IBD do not have
effective and should be used for long-term dietary vomiting, weight loss or decreased appetite, but it
management of intolerance or allergy to prevent nutri- can occur in cats with severe disease or disease affect-
tional deficiencies or excesses. ing the small and large bowel together.

The presence or severity of diarrhea or hema-
IDIOPATHIC INFLAMMATORY BOWEL tochezia does not correlate with the histologic grade
DISEASE (IBD)* of disease.

Classical signs
Diagnosis
● Diarrhea ranges from soft, mucoid blood-
Hematologic abnormalities are uncommon, but are
streaked feces to liquid diarrhea (more
consistently associated with severe colonic IBD and
characteristic of small bowel disease).
usually represent a typical stress response.
● Other signs may include vomiting,
anorexia, weight loss and lethargy. The most common biochemical abnormalities (when
they occur) are elevated hepatic enzyme activities and
hypokalemia. Hyperglobinemia may also occur.
Pathogenesis
Fecal floatation should be performed to rule out intes-
The etiopathogenesis of colitis or IBD is unknown. tinal parasitism, including giardiasis and coccidia.