Many feline health conditions may manifest themselves in diarrhea—the abnormally frequent passage of watery, sometimes oddly colored (gray or yellow), and uncharacteristically foul smelling stools. In most cases, fortunately, the condition will be short-lived, either self-resolving or readily remedied with a change of diet. In some instances, however, diarrhea can be a manifestation of a deeply rooted, possibly life-threatening condition.

A wide range of afflictions can cause fecal matter to move through a cat’s intestinal tract too rapidly. This results in the insufficient absorption of nutrients, water, and chemicals called electrolytes—substances such as potassium that regulate the flow of water molecules and electrical charges across cell membranes. When this occurs, the animal’s bowel movements may be frequent and perhaps uncontrollable, and its evacuated fecal matter will be soft, watery, and possibly streaked with mucus or blood.

The condition may be of brief duration, readily treatable, and ultimately harmless. An abrupt change in diet, for example, may cause a cat to experience diarrhea for a few days. Likewise, a stressful situation—a long automobile trip or a weekend stay at a veterinary clinic—may produce a brief episode of loose bowels. Kittens may be at elevated risk as their digestive systems adjust to the introduction of solid food.

In most cases, any abnormality in defecation in an adult cat—if not clearly attributable to a dietary problem—is likely to be directly associated with the gastrointestinal tract and will most often be attributable to an inflammatory, infectious, or neoplastic disorder. But extended or recurrent bouts of diarrhea may also indicate a serious underlying condition whose sources are external to the intestinal tract, such as a hyperactive thyroid gland, a disease of the kidney or liver, a neurologic abnormality, a viral infection, an immune system abnormality, feline distemper (panleukopenia), or lymphoma, a tumor that develops in an animal’s lymph nodes.

Diagnosing an excretory system disorder and identifying the specific cause will depend largely on the specific cat’s age and the intensity of the clinical signs. If the diarrhea persists for longer than a day or two and the cat is also showing systemic signs, such as poor appetite, lethargy, or vomiting, you should seek veterinary care as soon as possible.

While there are many medications and other therapies available that may effectively relieve feline diarrhea, it is most important for a veterinarian to examine an affected animal as soon as the clinical signs are noticed, as some over the counter medications can be harmful to cats.”