Clostridium perfringens has been associated with chronic diarrhea in dogs and cats. Although the pathogenesis of C. perfringens enterotoxicosis (CPE) has not been determined, the organism is typically sensitive to tylosin administration.13 Tylosin, a macrolide antibiotic, is available as a powdered formulation containing about 2,600 mg of active agent per teaspoon
(Tylan Soluble—Elanco); it may help to mix the powder with confectioner's sugar in a ratio of 1:1 to achieve a more useable
concentration. The resulting formulation would then contain about 1,300 mg of active agent per teaspoon. Tylosin can be given
with meals (Table 2),14 but cats may refuse the powder even when mixed with appetizing or strong-smelling foods, and it may be easier to administer
the drug in a capsule. In addition to its antibacterial properties, tylosin appears to have some immunomodulatory effects,
making it a possible adjunctive treatment for IBD.
Campylobacter species have been associated with mucoid diarrhea in young cats. Although it is uncertain how useful antibiotic therapy is
in this disease, erythromycin, a macrolide antibiotic, is the recommended therapy in people and animals15 (Table 2).
Management of chronic diarrhea is usually not complete without considering dietary intervention. This may be beneficial either
alone or in conjunction with primary treatment of the underlying disease. A range of diets is available for cats with chronic
diarrhea and includes highly digestible, high-fiber, and exclusion diets.
Highly digestible diets
An ideal highly digestible diet should contain a single protein source, no allergenic additives or flavorings, and nutrients
with protein digestibility > 87% and carbohydrate digestibility > 90%.16 High digestibility minimizes intestinal bacterial metabolism and ensures ease of nutrient assimilation when digestive function
is poor. It also results in less fecal volume in many cases. These diets can be used for a variety of gastrointestinal (GI)
diseases but have resulted in improved fecal scores in cats with chronic, nonspecific diarrhea.
High-fiber diets may be helpful in cats with large bowel diarrhea. Insoluble fibers increase fecal bulk, improve intestinal
motility, and bind nonabsorbed fluid in the intestinal lumen. Soluble fibers decrease fecal bulk, bind nonabsorbed fluid into
gels, and increase the concentrations of beneficial bacteria. Soluble fibers are fermented by intestinal bacteria into short-chain
fatty acids, which are the preferred energy source for colonocytes. They also decrease intestinal intraluminal pH, thereby
inhibiting opportunistic pathogens such as Clostridium and Salmonella species. Most high-fiber diets contain both soluble and insoluble forms to provide the benefits of both.
Elimination diets are indicated if food allergy or food intolerance is suspected. Many elimination diets are available that
contain either hydrolyzed proteins or novel proteins along with novel carbohydrate sources. The term hydrolyzed refers to proteins that have been cleaved into small fragments, thereby minimizing antigenic stimulation. Elimination diets
can be prepared by owners at home, but they must be nutritionally balanced to prevent vitamin and mineral deficiencies if
long-term use is planned.
When selecting an elimination diet, it is important to choose a protein source to which the patient has not been previously
exposed since prior sensitization may have occurred. Elimination diet trials should last at least eight to 12 weeks. Owner
compliance is often a limiting factor because strict adherence to the therapeutic diet is necessary to maximize its efficacy.
To fully assess the therapeutic success of an elimination diet, the patient should be challenged with the original diet to
verify return of clinical signs. Often this is not possible because owners are reluctant to risk a relapse in a well-controlled