Dog food, treat and supplement formulation affects pets’ microbiota, including the communities of microorganisms harbored by dogs’ intestinal tracts. Recipes’ ratios among fiber, resistant starch and protein can influence the quantity and type of intestinal microbiota species. Prebiotic formulations and supplements for dogs have grown in popularity, following human trends toward digestive health. However, not all human prebiotics are ideal for jumping into the pet market. Researchers examined how three dietary fibers influenced dogs’ health. They noted one fiber source that may not be ideal for dog supplements, although common in human products. Psyllium seed husks, found in human brand Metamucil, also appears in dog supplements.
“I was interested in how different dietary fibers influence the composition of the intestinal gut flora or microbiota,” study co-author Silke Salavati, PhD, chaired professor of small animal gastroenterology at the University of Edinburgh, told Petfood Industry in an email. “Some of these, particularly psyllium seed husk, have been used for many decades in veterinary medicine, and have been associated with all sorts of health claims regarding gut function in dogs (and cats), but there is very little actual information on the mechanism by which any of those potential benefits are achieved.”
Psyllium as a dog prebiotic supplement
Salavati’s team wanted to assess the effect of psyllium, but needed something to compare it to. For one comparison, they decided to use resistant starch from banana flour. Like psyllium, resistant starches have potential health benefits, although often unproven in dogs, she said.
“The third fiber, methylcellulose, is a type of non-digestible fiber, and we wanted to use this as a control,” she said. “We did not expect it to have any health benefits but possibly simply pass through. However, methylcellulose is also occasionally used as a laxative, so it had a dual ‘control’ function here.”
The study included 17 healthy dogs. The journal Access Microbiology posted the study.
Some of the results were contrary to what Salavati’s team expected. Although the psyllium fiber did not cause dramatic changes in the dogs’ fecal microbiota composition, it unexpectedly related to shifts in both richness and diversity of bacterial groups that would not necessarily be considered favorable when it comes to gut health, she said.
“Hence our main conclusion is that psyllium, when observed to have a positive clinical effect, might not elicit these effects via modulation of the microbiota but other mechanisms, and that we would not necessarily recommend this specific resistant starch as a prebiotic or health-promoting dietary fiber in dogs,” Salavati said.
Overall though, observable fecal characteristics and animal demeanor did not change much throughout the supplementation phases, she said, despite the expected diarrhea in some dogs on the methylcellulose diet.
While her team’s work found evidence that psyllium may have draw backs as an ingredient for dog supplements, many more dietary fibers remain to be studied.
“There are hundreds of different types of dietary fibers, including resistant starches, so these conclusions cannot be extrapolated to the entire group or even other resistant starches,” she said. “These would all need to be tested individually.”