Written by Bonnie Markoff, DVM, ABVP

No one likes having diarrhea. Luckily, for all of us, most cases of diarrhea are short-lived and resolve themselves within a day or two. I’m not sure if there is anything in veterinary medicine more frustrating than chronic, or long-term, diarrhea.

Whenever a dog or cat presents to Animal Care Clinic for chronic diarrhea, we start with a long conversation. History taking can be the most important test we do in finding the cause. We will want to gather a complete dietary history, deworming history and travel history. A thorough physical exam is also important. In most cases, further evaluation will be needed.

Parasites are a very common cause of diarrhea in pets. A proper fecal flotation should be performed to look for parasite eggs. There are good and bad ways to run this test. A proper float uses a large volume of feces (at least the size of a tootsie roll) and does not rely on a small volume scooped form the anus or the little bit that fits in those greenish collection containers that are sometimes sent home with owners. The type of fluid that is used and treatment of that fluid is also important. In other words, not all fecal floats are equal. Always ask for a Zinc sulfate, centrifugal float. Otherwise, many parasites can be missed. The most common diarrhea-causing parasites we see in dogs and cats include roundworms, hookworms, giardia, coccidia and whipworms. In cases of chronic diarrhea, we will treat for these parasites even if the tests are negative.
Systemic diseases can also cause diarrhea. A full lab panel including blood chemistry, complete blood cell count, thyroid level and urinalysis will usually be performed. We may also want to check blood levels of vitamin B12 and pancreatic enzymes. If an animal has a low-grade liver, intestine or pancreas problem, we want to know about it as soon as possible. In some situations, x-rays or ultrasound may be warranted.

Infectious agents may also play a role in diarrhea. Cats get infested with a protozoon called tritrichomonas. Dogs can get Ehrlichiosis. Animals who have been in other parts of the country could have fungal infections or other diseases you may never have heard of. Cats with Feline Leukemia or the Feline AIDS virus can have diarrhea. In middle-aged to older patients we have to consider cancerous causes.

Diet is often at the bottom of diarrhea. Many animals have dietary intolerances or a disease called inflammatory bowel disease. Sometimes, just a change in diet will solve the problem. You can always start by using a premium pet food. I define “premium” as a diet that never changes its ingredients (fixed formula), has been through AAFCO feeding trials, and is designed for specific life stages rather than being balanced “for all stages of life.” There are not many diets that fit these rules! It is important to be sure that pets with chronic diarrhea do not eat anything aside from the premium diet – no table scraps, special treats, trash, goodies from the backyard, junk at the beach, etc, etc.
If your pet is properly dewormed and is eating only a premium diet, but still has diarrhea, you will need veterinary help in solving the problem. We may want to try a diet high in fiber or one with no fiber at all. Your pet may need a limited antigen diet (only 2 ingredients), a hydrolyzed diet (all proteins broken down) or specially formulated homemade diet.

The veterinarians at Animal Care Clinic can help you to determine just what your pet needs based on the physical exam, history and perhaps a few of the tests I’ve listed. Give us a call!