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Dr. Will Draper

Your pet's digestive system, just like yours, is home to billions of bacteria that keep their gut running smoothly.

Probiotics, often sold as supplements, are living microorganisms very similar to these resident bacteria. When your cat or dog is troubled with gastrointestinal problems like diarrhea or constipation, can these tiny organisms accomplish the improvements often attributed to them?

Common Digestive Problems in Dogs and Cats

The digestive systems of cats and dogs are more similar than different. Although cats generally have smaller stomachs and shorter digestive tracts than dogs, both process their food in the stomach, with nutrients and water later absorbed as it moves along through the intestines.

"The gut is the largest immune organ in the body," says Susan G. Wynn, DVM, a veterinary nutritionist in Atlanta. Its job is to allow absorption of food, while excluding elements like bacteria and toxins, yet "sometimes these defenses break down."

That breakdown can lead cats and dogs to experience similar digestive upsets, including vomiting, diarrhea, and constipation. The cause of gastrointestinal problems for dogs is often related to their tendency to eat things they shouldn't, while cats may suffer digestive system upset as a result of parasites in their prey.

For cats and dogs, studies show that a healthy population of gut bacteria is vital to a fit gastrointestinal tract. "Gut flora and mucosa act as barriers against gut pathogens," says Kara M. Burns, MS, MEd, president of the Academy of Veterinary Nutrition Technicians. They also play a vital role in removing toxins, enhancing digestion, and out-competing disease-causing microorganisms.

Can Probiotics Help Your Pet?

Although studies are ongoing, some research shows that when your cat or dog experiences digestive problems, probiotics can be beneficial, says Ann Wortinger, BIS, LVT, program chair of veterinary technology at Sanford-Brown College in Dearborn, Mich. Probiotic "good" bacteria can lower intestinal pH, helping to not only boost their own numbers, but to lower the numbers of disease-causing bacteria in your pet's gut, while making it harder for potentially disease-causing pathogens to set up shop in the small intestine, Wortinger explains.

Probiotics might potentially help in many ways, Wynn tells WebMD, such as boosting poor immune function, addressing bacterial imbalance, or by enhancing the health of the cells in the tissue of your pet's gastrointestinal tract that produce digestive enzymes. "They may also help with digestion by providing their own digestive enzymes," she adds.

Marla J. McGeorge, DVM, a Portland veterinarian specializing in cat care, uses probiotics in the management of antibiotic-associated diarrhea, as well as in patients she feels could benefit from general immune system support, such a cat fighting an infection.