While some research suggests that lifelong training and an enriched diet could slow cognitive aging in dogs, most of those studies focus on dogs in a laboratory setting. Few studies have explored aging in pet dogs.

An international team of researchers led by Durga Chapagain, DVM, MS, PhD, of the University of Veterinary Medicine in Vienna, Austria, sought to correct that omission in a new study.

Chapagain and her colleagues enrolled 119 pet dogs, all over six years of age, in the randomized trial. All were fed one of two diets over the course of a year—either a control diet of regular dog food or an enriched diet that included nutrients like antioxidants, omega-3 fatty acids, tryptophan, and phosphatidylserine.

Owners filled out a questionnaire to detail their dogs’ training history.

At the beginning and end of the one-year study, the researchers tested the dogs’ cognitive ability using the Modified Vienna Canine Cognitive Battery (MVCCB), which consists of 11 subtests that measure individual differences in a set of tasks gauging general, social, and physical cognition, as well as related behaviors.

Their findings showed that, in general, the aging dogs experienced declines in four out of six total factors addressed by the MVCCB: problem-solving, sociability, boldness, and dependency. The two other factors, trainability and activity independence, showed no change with age.

Perhaps more significantly: elderly dogs who received lifelong training and ate a nutrient-enriched diet for a year didn’t perform any better on thinking tests than dogs who received less training and ate a regular diet.

NEWStat reached out to lead author Chapagain to learn more.

NEWStat: What’s the difference between running these tests on dogs in a laboratory setting and running them on pet dogs who live at home with their owners? Why would the results be different?

Durga Chapagain: Most of the dogs in laboratory studies are a homogenous population kept in standardized housing, whether they’re alone or in pairs or groups, with very limited social activity, and low stimulation/training. In general, these dogs are fed mostly similar diets during their lifetimes. However, the majority of pet dogs have a completely different experience: they’re available in multiple breeds, live in different housing conditions with one or more people in the household, sometimes with multiple dogs, and eat different brands of dog food during their lifetime. And they get different kinds of stimulation with different forms of training. So, the effect of an enriched diet may vary in these two populations of dogs due to those differences. That needs to be taken into consideration when trying to determine whether or not an enriched diet has any effect on dogs’ behavior and cognitive function.

NEWStat: What about enriched dog food that’s marketed for senior dogs?

 DC: There are different brands of senior-dog diets in the market but very few have been tested for pet dogs to [gauge] whether these enriched diets have any influence in dogs’ behavior and cognition during aging. A majority of these diets have been tested in laboratory-raised beagle dogs, who have shown beneficial effects on learning, memory, and, to some degree, attention. That’s why we designed a study to find out whether or not an enriched diet showed any effect on different measures of cognition and behavior in successfully aging pet dogs older than six years. The next step would have been to test the enriched diet in dogs showing symptoms of cognitive dysfunction.

NEWStat: Do your findings rule out the idea that specialized senior diets can slow the aging process in older dogs?

 DC: Previously, we had very little understanding of the effects of an enriched diet in dogs other than laboratory dogs. Those studies have claimed that these senior diets are very effective. But we advocate that, in order to claim whether or not these diets have any effect on dogs’ cognition and behavior, we need to test these diets in the general dog population—in pet dogs, working dogs, sports dogs, service dogs, therapy dogs, etc. We also need to test them in two separate populations: successfully aging dogs, and dogs suffering from one or multiple symptoms of canine cognitive dysfunction to see what effects diet has on these two populations.

We should be cautious about generalizing the findings on studies on laboratory dogs to all dog populations, as well as advertising claiming that certain food brands are effective for pet dogs per se.

Based on our results, we would not like to claim that enriched diets in general are not effective but would rather have veterinarians caution clients that before buying a senior diet or choosing a certain senior food brand, pay attention to those diets’ health claims for their particular dog. As pet dogs vary so much and in different aspects, our results showed that we would need a much larger dog sample to show whether or not an enriched diet has any effect on cognition and behavior in successfully aging dogs older than six years. So, we’d like to refrain from making a strong claim about the effectiveness of an enriched diet.

NEWStat: Can anything help reverse cognitive decline in older dogs?

DC: We have shown in a previous study that lifelong training can help older pet dogs to retain attentiveness.

Photo credit: © Gettyimages/Malaui