Ingredients such as lentils, beans and field peas typically used in grain-free dog foods are safe for healthy dogs, according to new University of Guelph research.
It’s a reassuring finding for dog owners worried about grain-free diets, which have surged in popularity and now make up almost half of the dog food market in Canada. The diets have been under scrutiny after “pulses” – the collective term used for peas, lentils and beans – became associated with a serious heart condition in dogs called dilated cardiomyopathy, or DCM.
This latest U of G research, which appears this month in The Journal of Nutrition, found that dogs fed diets containing up to 45 per cent whole pulse ingredients and no grains over 20 weeks showed no indications of heart issues.
As well, the dogs’ body composition altered less than 0.1 per cent from baseline no matter which diet they were on, suggesting they also maintained lean body mass.
“This study is the longest, controlled feeding study to date to assess cardiometabolic health in healthy adult dogs fed pulse-inclusive diets,” said lead author Dr. Kate Shoveller, a professor in the Department of Animal Biosciences in the Ontario Agricultural College and Champion Petfoods Chair in Canine and Feline Nutrition, Physiology and Metabolism.
Dr. Adronie Verbrugghe, clinical studies professor and Royal Canin Veterinary Diets Endowed Chair in Canine and Feline Clinical Nutrition at the Ontario Veterinary College (OVC), added: “This research is important to help veterinarians make evidence-based diet recommendations for their patients. Some dogs might be healthy, but others could have specific health conditions for which protein sources and content are targeted.”
Pulses a dependable protein alternative in pet food
Pulses are an attractive protein source in pet foods and need to be included in plant-based dog food formulations to provide sufficient dietary protein. Yet there have been concerns pulses may be limited in key amino acids for the body to make taurine, needed for proper heart.
Poor bioavailability of key amino acids has also been linked to inadequate protein absorption and muscle wasting in dogs.
To investigate the potential effects of pulse ingredients on cardiac function of healthy dogs, the researchers recruited 28 Siberian huskies for a randomized, controlled trial. Huskies are not genetically at risk of DCM, meaning any changes to their heart health would reflect diet, not genetics.
Each dog was assigned to a diet containing either zero, 15, 30 or 45 per cent whole pulse ingredients, specifically green and yellow peas, pinto beans, chickpeas and lentils. All diets included chicken as the animal protein source and were formulated with the same protein and fat levels.
All pulse ingredient concentrations reflected current formulas in commercial dog foods, said lead author Pawanpreet Singh, a U of G PhD student in animal biosciences.
“We wanted to keep all aspects of the diets the same except the amount of pulse ingredients so that any changes we saw in the dogs’ cardiac function could be attributed to the differing amounts of pulses and not nutrient intake,” said Singh.
No changes to dogs’ body composition or heart function
Champion Petfoods funded the study and all experimental diets were processed in its facilities. The company did not influence the findings or conclusions of the study.
Echocardiograms were performed by veterinary cardiologist Dr. Shari Raheb, a professor in OVC’s Department of Clinical Studies, to detect heart changes. Singh routinely collected blood samples to assess cardiac biomarkers or amino acid changes.
Verbrugghe and registered veterinary technician Shoshana Verton-Shaw performed scans to assess body composition at the beginning and end of the study, and all dogs were weighed every week.
“We took the highest precautions to monitor the health of these dogs. We made sure to conduct monthly health checks and evaluate their heart blood markers to make sure there were no signs of cardiac stress,” said Singh.
“We found that regardless of the amount of pulses consumed, none of the dogs showed changes to indicate the development of DCM or body composition changes.”
Shoveller said previous clinical studies were not able to pinpoint whether pulse ingredients played a role in DCM in dogs not genetically predisposed.
“Our data suggest the inclusion of pulse ingredients in dog food is not a causative factor and emphasizes the importance of understanding the nutrient composition of each ingredient and ensuring that foods exceed minimum nutrient requirements,” she said.
“Ultimately, pulses are a dependable protein alternative in the food industry and this study emphasizes their safety even when incorporated at high concentrations.”
Dr. Kate Shoveller
Dr. Adronie Verbrugghe