There has been a belief among veterinarians that some dog breeds are more sensitive to pain than others. And new research suggests they are right. But the breeds commonly thought to be particularly pain-sensitive may not be the ones that truly are. That’s because vets appear to be making their determinations based on dogs’ reluctance to come over to them and interact in novel situations rather than on the animals’ actual sensitivity to pain.
Consider that in prior research, more than 1,000 veterinarians who responded to a survey reported that they generally considered German shepherds to be highly sensitive to pain. But in subsequent tests during which German shepherds had increasing pressure applied to the top of a paw from both a blunt-tipped object and a sharp-tipped object, they demonstrated that they had a relatively high threshold for responding compared to a number of other breeds and therefore were not especially pain-sensitive. That is, it took them long-
er to pull their limb away than, say, border collies. At the same time, another test found that German shepherds can be rather reluctant, or cautious, about coming over to a stranger — which may be why veterinarians tend to rate them as particularly sensitive to pain.
The latest findings were part of a project conducted by investigators at North Carolina State University’s College of Veterinary Medicine. In a study reported in the journal Frontiers in Pain Research, they gave 150 dogs of 10 different breeds various tests for tolerance of physical pain and also measured the dogs’ behavior in response to strangers and strange objects. Lest you think the dogs were forced to endure pain, they were not. As soon as a dog wanted to withdraw — from the increasing pressure or heat of a stimulus applied to the foot — she or he could. But some breeds simply were more apt not to be bothered by the stimulus for a longer period of time than others (although never exceeding 20 seconds, the safety cut-off for this type of test). That is, they exhibited a higher pain threshold.
It was a similar scenario observing whether the dogs were reactive in a strictly behavioral sense, meaning the canines had free agency in that part of the experiment, too. They were brought to a pen with a plush monkey that made noise and could either “greet” the unfamiliar object or avoid it completely. In another behavioral test, dogs listened to a stranger in a hooded sweatshirt talking loudly into a phone. They could walk over to the stranger or not, and after 30 seconds, the stranger removed the hood and greeted the dog in friendly tones. It was the dog breeds that tended to shy away from the stranger on the phone that veterinarians rated as being more sensitive to pain. The vets may have been conflating reactivity based on fear and anxiety with a low pain tolerance. As this study makes objectively clear, the two are not the same.
Implications for the future
Research on people has suggested that those with red hair perceive pain differently than those with brown or blonde hair. They may be more sensitive to certain types of pain and therefore may need higher doses of certain analgesics (while requiring lower doses of others). They also may require more anesthesia than people with other hair colors. One study found that women with red hair need 20 percent more anesthetic drugs than women with darker hair in order to remain sedated.
Just as there is some evidence that there may be identifiable differences in people that can predict who is more prone to pain, it is now being found that the same may very well be true of different kinds of dogs. All dogs should be treated tenderly at the doctor’s office, of course, with lots of loving care, especially since they can’t tell us what they are experiencing; that is, it is better to err on the side of being too careful.
But down the line, the veterinary community may find that certain breeds need more of certain pain medications, or a lighter touch during procedures that involve a hands-on approach, or a different anesthesia protocol. And, as this research indicates, that could have nothing to do with a dog’s reactivity at the vet’s office. Stress about being examined by the doctor — a relative stranger — does not automatically equate with a lower pain tolerance.
Lead researcher Rachel Caddiell, PhD, says that “next steps for this work include investigating if veterinarians’ perceptions impact pain identification and treatment across dog breeds, as well as how we can best incorporate our findings in teaching best practices for pain management in the future.”
