Recent research by North Carolina State University has revealed unexpected disparities between perceived and actual pain sensitivity across different dog breeds.
Interestingly, these disparities don’t always align with the assumptions held by both the general public and veterinarians concerning breed-specific pain sensitivity.
Furthermore, the research suggests that a dog’s temperament, especially how it interacts with strangers, may influence veterinarians’ perceptions of pain sensitivity in different breeds.
“Veterinarians generally agree on their ratings of pain sensitivity in dogs of various breeds. However, their opinions often conflict with those of the public,” says Margaret Gruen. She is an associate professor of behavioral medicine at NC State and a co-author of the study.
“We were keen to find out whether these beliefs were accurate. For instance, if we tested the sensitivity thresholds of 15 dogs from 10 breeds rated as having high, medium, and low sensitivity, would we notice any differences? Would these differences align with what veterinarians believe? Or could these perceptions be influenced by a dog’s emotional reactivity and behavior during interactions with a veterinarian?”
To probe these questions, the researchers selected healthy adult dogs from 10 breeds, both male and female.
The breeds were ranked by veterinarians for levels of pain sensitivity.
The first group was ranked as high (like the chihuahua, German shepherd, Maltese, and Siberian husky).
The second group was ranked as average (like the border collie, Boston terrier, Jack Russell terrier).
The third group was ranked as low (like the golden retriever, pitbull, Labrador retriever) pain sensitivity.
These breeds represented a broad range of perceived sensitivity. In total, 149 dogs participated in the study.
Taking cues from human clinical medicine, the NC State team measured pain sensitivity in these canines. “We typically use reactivity to external stimuli as a measure in neurology and pain clinics for humans,” says Duncan Lascelles.
Lascelles is a professor of translational pain research at NC State and another co-author of the research. He explains further, “For this study, we have adapted these measures for pet dogs.”
The team gauged each dog’s sensitivity to pressure and temperature by pressing a pressure tool and then a warm thermal probe against the top of the back paw.
As soon as the dog moved its paw, the stimulus was removed. Each test was conducted five times, and the outcomes were used to quantify sensitivity.
The researchers also performed two emotional reactivity tests to gauge how the dogs responded to unfamiliar people or objects. Also, to simulate some of the stressful elements of a vet visit.
These included the ‘novel object test’ and the ‘disgruntled stranger test’. The novel object was a noisy, moving stuffed monkey. The disgruntled stranger was a person engaged in a loud phone call before calling the dog over.
The team compared the results of these sensitivity tests with questionnaires completed by veterinarians and the general public about breed-specific pain sensitivity.
The study’s findings revealed that genuine differences exist in pain sensitivity thresholds between breeds. However, these differences don’t always correspond to the veterinarians’ rankings.
For instance, Maltese dogs were found to have a high sensitivity threshold, or low pain tolerance. They responded rapidly to pressure and temperature stimulus. This matched veterinarians’ assessments.
But Siberian huskies, thought to be highly sensitive according to veterinarians, actually fell into the mid-range sensitivity. In fact, several larger breeds considered sensitive by veterinarians exhibited an average-to-high pain tolerance.
Notably, the researchers found that dogs less likely to engage with the novel object or disgruntled stranger were often rated as having lower pain tolerance.
This raises a question – could a dog’s stress level and emotional reactivity during a vet visit impact a veterinarian’s pain tolerance assessment for that breed?
This research provides food for thought for veterinarians and dog owners alike. The study’s findings stress the need for a deeper understanding of our canine friends.
“These behavioral differences might explain the different veterinarian ratings, but not actual pain tolerance between breeds,” says Lascelles.
Lascelles continues, “This study is exciting because it shows us that there are biological differences in pain sensitivity between breeds. Now we can begin looking for potential biological causes to explain these differences, which will enable us to treat individual breeds more effectively.”
“On the behavioral side, these findings show that we need to think about not just pain, but also a dog’s anxiety in the veterinary setting,” Gruen says. “And they can help explain why veterinarians may think about certain breeds’ sensitivity the way they do.”
The research appears in Frontiers in Pain Research and was supported by the American Kennel Club Canine Health Foundation. Former NC State Ph.D. student Rachel Caddiell is first author.
Rachael Cunningham, former NC State postdoctoral scholar and current small animal surgery resident at Kansas State University, and Philip White, statistician at Brigham Young University, also contributed to the work.
The story of dog evolution begins around 40 million years ago with a weasel-like animal called Miacis. It is considered the common ancestor of both dogs and cats.
However, the true canid family, which includes dogs, wolves, and foxes, emerged approximately 34 million years ago.
It’s believed that around 20 to 40 thousand years ago, the evolutionary path of domestic dogs (Canis lupus familiaris) diverged from that of wolves. The exact timing is still debated among scientists.
A plausible theory is that gray wolves, the closest wild relatives to domestic dogs, were attracted to human camps to scavenge on leftovers. Over time, some wolves could have developed a tolerance for humans.
This led to a symbiotic relationship where humans provided food and protection. In return, the wolves helped in hunting, guarding, and companionship.
The process of artificial selection likely took over from there. Humans might have started breeding wolves. They selected the wolves by favoring those with desirable traits such as tameness, smaller size, or a keen sense of smell.
Over many generations, these early canines began to differ from their wolf ancestors physically and behaviorally. This eventually gave rise to what we now know as dogs.
Dogs were the first domesticated species and their close relationship with humans has shaped their evolution in a unique way. Throughout history, humans have selectively bred dogs for various purposes.
This widespread breeding has resulted in the wide variety of breeds we see today. Each dog breed was selected for certain traits. These include herding sheep, hunting game, or providing companionship.
However, it’s important to note that despite thousands of years of divergence and selective breeding, domestic dogs are still a subspecies of Canis lupus, the gray wolf. The two share over 99% of their DNA.
As we uncover more about the canine genome and ancient archaeological sites, our understanding of dog evolution continues to deepen. Nevertheless, the exact circumstances and timing of the early domestication process remain elusive and the subject of ongoing scientific research.