Things Your Vet Might Recommend for Your Pet’s Diarrhea

SFSBlog_diarrhea_madartichoke_together_FlickerCCDiarrhea becomes a fact of life for most of our pets at some point or another. If the diarrhea persists for more than a few days or is recurrent, it’s a good idea to check in with your veterinarian even if your dog or cat seems to be feeling just fine otherwise.

Beyond performing a thorough physical examination, there are a number of things your veterinarian may recommend. Below is the rationale behind these recommendations.

Diagnostic testing

Whenever possible, having a diagnosis in hand (ugh, given the topic, this sounds kinda gross) is the very best path for getting the problem resolved. A variety of diagnostic tests are readily available to determine the cause of your pet’s diarrhea. The usual starting point is a fecal exam to look for intestinal parasites. Next come blood and urine testing to rule out underlying issues such as hyperthyroidism (kitties), liver or kidney disease. Specialized blood testing looking for issues such as inadequate production of digestive enzymes, decreased levels of folate or cobalamin (both are B vitamins necessary for normal gut health), or hormonal imbalances that can cause diarrhea may be indicated. If results from these tests fail to provide a diagnosis, imaging , typically x-rays and/or abdominal ultrasound, is the usual next step. Lastly, your veterinarian may recommend getting an up close and personal look at the bowel and collection of biopsies by way of either surgery or endoscopy.

Empirical therapy

Empirical therapy refers to administration of treatment without knowledge of the underlying diagnosis. Such therapy will likely be recommended for your pet’s diarrhea should you and/or your veterinarian determine that the testing needed to establish a diagnosis isn’t feasible. Listed below are empirical treatments commonly recommended for dogs and cats with diarrhea.


Intestinal parasites are a common cause of diarrhea in dogs and cats. Depending on the life cycle of the worms, sometimes they and/or their eggs simply don’t show up on fecal screening. For this reason, your veterinarian may recommend empirical deworming with fenbendazole, a highly effective broad spectrum executioner of most intestinal parasites.

Food trial

Your veterinarian may recommend a novel protein diet to help rule out a food-responsive enteropathy, in essence, a food allergy that can cause diarrhea. Back in the day when I was just a pup, we would prescribe lamb for such food trials. Lamb has become such a common ingredient in commercially prepared foods, that, by the time they arrive at adulthood, most dogs have already been exposed to it. Nowadays, novel protein sources such as kangaroo, ostrich, rabbit, quail, alligator, and duck are commonly recommended. Some veterinarians prefer hydrolyzed protein diets in which the protein has been broken down into molecules that are so small they escape detection by the immune system, thus avoiding an allergic reaction.

When fat is not properly absorbed within the gut, diarrhea is a predictable outcome. For this reason, your veterinarian may recommend a diet with reduced fat content.

The addition of fiber to the diet can be of benefit for diarrhea. Canned pumpkin is a commonly recommended source of fiber- good luck getting your kitty to eat this!

Food trials are typically prescribed for a four to six week time period, although improvement is often observed within the first couple of weeks.


Just like us our pets have different types of “normal” bacteria that reside within their gastrointestinal tracts. When there is shifting of bacterial populations such that there is overpopulation of some and crowding out of others, a variety of gastrointestinal symptoms, including diarrhea, can develop. This condition is referred to as antibiotic responsive enteropathy (formerly known as small intestinal bacterial overgrowth or SIBO). Your veterinarian may recommend empirical treatment with a particular type of antibiotic along with a probiotic. The hope is that this combination will restore a healthier balance of bacterial flora within the gut.

I want to emphasize that bacterial infections within the bowel are as rare as the proverbial hen’s teeth. Any antibiotic you give for diarrhea should be aimed at treating antibiotic responsive enteropathy rather than infection. The exception to this is the diarrhea called granulomatous colitis, also known as histiocytic ulcerative colitis. Sometimes referred to as “Boxer colitis” because it occurs almost exclusively in Boxer dogs, this disease is caused by bacteria and responds dramatically to treatment with the antibiotic enrofloxacin (Baytril).

Other medications

Should the above steps fail to remedy your pet’s diarrhea, your veterinarian may prescribe any one of a number of empirical medications. They run the gamut from gut motility modifiers to intestinal coating agents to anti-inflammatory medications. Corticosteroids such as prednisone or prednisolone are recommended as empirical treatment for diarrhea. Steroids have the potential for lots of side effects, so thorough discussion with your veterinarian should precede their use.

Bear in mind that none of these empirical therapies are an ideal substitute for obtaining a diagnosis. If your pet’s diarrhea fails to resolve in response to any of the treatments recommended, revisiting the option of further diagnostic testing is warranted.

In general, veterinarians who specialize in internal medicine have the most expertise diagnosing and treating chronic or recurrent diarrhea. Your time and resources, and, most importantly, your pet may be best served by working with such a specialist.

Has your pet had chronic diarrhea? If so what was the cause? What treatment fixed or failed to fix the problem?

Best wishes,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.

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2 Comments on “Things Your Vet Might Recommend for Your Pet’s Diarrhea

  1. Hi Becky,

    Metronidazole is a commonly used medication for diarrhea. It works well against some parasites, is an anti-inflammatory medication in the bowel, and may be the drug selected to treat antibiotic responsive enteropathy (formerly known as small intestinal bacterial overgrowth).

    Best wishes to you and your Pug,

    Dr. Nancy

  2. What about metronidazole? My 5 year old pug has had intermittent diarrhea since she was 6 mos old and had pneumonia. My vet said all the antibiotics she had to have then messed up her system. (He did run several tests but found nothing i.e. parasites, allergies.) Metronidazole is the one thing that works for her now. She also was on Tylan powder for a while when the diarrhea was really bad and that helped.

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