Dear Doctor – Our experts address persistent diarrhea in cats

Why does one cat in my home have soft stools but not the other


[From Tufts December 2011 Issue]

I have two 9-year-old Tonkinese sisters. One has always had firm stools and the other, in the last year, has had soft stools and diarrhea. They eat only Wellness Core dry food — no treats or people food.

They are strictly inside cats. I tried desperately to introduce them to canned food without success. The cat with the soft stools has a beautiful coat, clear eyes and appears very healthy. My veterinarian can’t find anything wrong with her. She does not have worms.

Do you have any suggestions as to what is causing the soft stools? What tests should my veterinarian perform? Should I be worried?
Sue DeMaria

Dear Sue: An occasional bout of diarrhea in cats is not uncommon and is usually no cause for concern. The fact that she has a beautiful coat, clear eyes and appears very healthy makes me think that you shouldn’t be overly worried at the moment. But clearly, persistent diarrhea is not a normal finding and requires veterinary attention. Left untreated, diarrhea can result in dehydration and electrolyte imbalances.

There are many possible causes of diarrhea in cats. Some common causes include a sudden change in diet, eating inappropriate items, gastrointestinal infections (bacterial, viral, protozoal), parasites, food allergy, pancreatitis and inflammatory bowel disease. The presence of blood and/or mucus in the diarrhea indicates that the large intestine is involved and that the cat may have colitis. Depending on the cause, cats with diarrhea may have no other signs of illness other than loose stool, or they may be systemically ill and show signs such as fever, poor appetite, weight loss and vomiting. Cats who are systemically ill should be checked by a veterinarian.

Acute cases may respond to symptomatic therapy such as withholding food for 12 to 24 hours and then feeding a highly-digestible therapeutic diet. Simple cases of intestinal parasites may only require routine deworming. Some cats cannot tolerate a particular brand of food, or a particular form of the diet (dry versus canned). In these cases, switching to a more appropriate diet resolves the problem. Cats with diarrhea for several days may require subcutaneous fluids and anti-diarrheal medications. Over-the-counter anti-diarrheal drugs intended for humans should NOT be given to cats with diarrhea, as many of these medications contain substances that may be dangerous or toxic to your cat. Always consult your veterinarian.

Depending on the severity and duration of the diarrhea, your veterinarian may want to perform some tests. Given the chronic nature of your cat’s diarrhea, at minimum your veterinarian should perform a complete blood count, chemistry panel, urinalysis and fecal exam. If the results are normal, a reasonable first approach with your cat might be to try a highly digestible therapeutic diet designed for cats with gastrointestinal problems. If no response is seen, additional tests, such as fecal culture, abdominal X-rays, ultrasound and perhaps endoscopy might be warranted to obtain a diagnosis.

Treatment of diarrhea will vary depending on the cause. Infectious causes may require antibiotics or other antimicrobial drugs. Food allergy often responds to a hypoallergenic diet. More serious conditions such as gastrointestinal cancer may require surgery and/or chemotherapy.
Arnold Plotnick, DVM, DACVIM
Medical Editor


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