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Almost a decade ago, the Canadian Veterinary Journal published a seminal study on probiotics for dogs showing that of 25 commercially available products tested, only two met criteria for quality control. Ten did not even list the bacterial counts in their merchandise, a critical point because probiotics are all about “good” bacteria flooding the GI tract to help calm a dog’s diarrhea or other gastrointestinal signs. Of the 15 that did list bacterial counts, only one in four actually contained what the label said. Some products mentioned bacteria that don’t exist, while others had bacterial counts that were too low to effect any beneficial changes in the gut.
Have probiotics gotten better in the interim?
“Unfortunately, not a lot has changed,” says the lead researcher, J. Scott Weese, DVM, an internationally renowned microbiology researcher at the Ontario Veterinary College. “We still have only limited evidence that probiotics work, and the few studies that have shown some impact haven’t been too impressive.” For instance, improvements in dogs’ bowel movements in clinical research — less constipation, less stress-related diarrhea — has ranged from about 10 to 30 percent. That’s statistically significant from a scientific point of view, but not something that would look like a very noticeable improvement to most pet owners.
For that reason, Dr. Weese says, “we’re still largely in a buyer-beware mode where it’s hard to have much confidence.” In fact, he comments, “some recent data from humans have shown that probiotics might actually delay restoration of normal bacteria in people and mice. It’s something we haven’t explored in dogs,” but it certainly raises a red flag.
The two probiotic products that passed muster for quality control in Dr. Weese’s research are FortiFlora and Prostora. “Additionally,” he says, “a newer product that wasn’t around when we did the original testing is VSL#3, which has been shown to have some positive impacts in dogs with chronic diarrhea.
“It is impossible to predict whether a probiotic will work,” Dr. Weese adds. No one knows ahead of time if it will cut down on, say, “explosive” bowel movements. “But trying one that has good quality control and some scientific data is reasonable. If there’s no response, then move on.”