Dog Walk Diarrhea: Cause for Concern?

When you walk your dog in the morning and pick up his poop with a waste bag, everything looks normal. During your afternoon jog, though, you notice that his poop has become softer and harder to pick up neatly and at another pit stop, it’s softer still. Besides the ‘yuck’ factor, is your dog’s diarrhea brought on by exercise something you have to worry about?

A study cited in the Journal of Veterinary Internal Medicine in 2005 documented how extreme stress would affect a dog's intestinal tract. The subjects were participants in the 2003 Iditarod sled dog race (1,100 miles in 10 days). The researchers found that in a substantial number of cases these extreme canine athletes had changes in how their intestines functioned. The related stress from their high activity levels seemed to cause small ulcers and made the intestine more permeable or "leaky".  This led to increased fluid in the intestinal tract and contributed to the abnormal G.I. signs, including diarrhea.

Your dog doesn’t have to be ‘mushing’ under extreme weather conditions to experience some of the side effects of exercise. According to Dr. Tim John, DVM of Snohomish, Washington, many pets experience diarrhea as a result of relatively normal things.

“I have seen many pets that when faced with stress have associated diarrhea," he says. "The stressors can be new environment or boarding situation or exercise.  Each animal is unique but they seem to consistently respond in this manner if they are predisposed. I have treated some pets with increasing fiber in their diet and that seemed to help some but not all of the patients. Exercise induced colitis is not a common problem but is a real clinical finding.”

Dr. Katy J. Nelson, DVM in Washington, D.C. and host of The Pet Show with Dr. Katy, explains that when you and your pet are exercising, blood supply gets redirected from the G.I. tract to the lungs and muscles and the body secretes enzymes that can increase gastric and intestinal motility in people and in pets.

“What you see at the beginning of your walk has already been digested," she says, "but as the walk progresses, what hasn’t been digested gets pushed out in semi-digested form."

Dr. Nelson recommends feeding the dog probiotics to crowd out any bad bacteria in the G.I. tract that could be contributing to the problem and not exercising too soon after a meal. A light treat is okay, as is bringing water along for your dog during the walk.

As far as whether dog walk diarrhea is a cause for concern, Dr. Nelson believes it isn't something that should keep you up at night.

“If your dog is doing it every day, I’d recommend a vet check it out to rule out problems (i.e. parasites, IBD or food intolerance)," she says. "But if it’s only occasional, it’s probably nothing to worry about.”