Pain sensitivity in dogs – It may not be what you thought (It definitely wasn’t what we thought with our old friend, Mutchie)
This blog is somewhat different from the blogs you are used to seeing from us. Our imagination was peeked when we noticed that one of our thermal devices was used to assess pain in different dog breeds, and we were sure any animal lover would be interested too.
How veterinarians perceive pain in different dogs
Veterinarians believe that different canine breeds have different sensitivity to pain, but there is no scientific or biological evidence to support that this is the case. Caddiell et. al. decided to put the veterinarians’ suppositions to the test and demonstrate whether or not pain sensitivity is breed specific. Their hypothesis was that there is no breed specific difference in pain perception and that the veterinarians’ suppositions are based on breed specific behaviors rather than pain thresholds.
Validating the perception on pain sensitivity in dogs using Quantitative Sensory Testing would also provide veterinarians a scientific basis for appropriately anesthetizing dogs under their care during medical interventions. The general belief among veterinarians regarding dogs’ pain sensitivity holds that Chihuahuas, German Shepherds, Maltese, and Siberian Huskies have high sensitivity to pain. Border Collies, Boston terriers, and Jack Russell terriers are thought to have an average sensitivity to pain. On the other hand, Golden Retrievers, Pitbulls, and Labrador Retrievers are thought to have low sensitivity to pain.
Quantitative sensory dog testing
Caddiell, et. al. examined pain threshold responses of 149 healthy dogs from 10 different breeds. Quantitative Sensory Testing (QST) was conducted among the different dog breeds in order to get an objective measure of pain sensitivity. Additionally, behavioral tests were conducted in order to assess whether the veterinarians “rate” a specific dog as sensitive based on true pain sensitivity, or because it exhibits specific e.g. nervous behavior. Pain thresholds were assessed with thermal and mechanical QST. While QST in humans relies on a verbal or response or a press of the button by the participant, with dogs, behavioral responses such as the withdrawal of his paw, a vocalization, or a sudden focus on the pain stimuli - is used as pain indicator. In addition, since the thermode was to be placed on the metatarsus and carpus of the dog, those areas were each shaved (an area of 2.24 cm2) to allow for unfettered placement of the thermodes.
The Electronic von Frey device was used to measure mechanical allodynia and hyperalgesia; the blunt probed Pressure algometer was used to measure pressure pain thresholds; and the Thermal Device used was the Thermal Sensory Analyzer TSA-II by Medoc Ltd, Advanced Medical Systems. Thermal pain sensitivity was measured using a Ramp-and-Hold (tonic heat pain) protocol in which the thermode temperature went up to 49°C, and stayed there for a maximum of 30 seconds, and the latency of the dog’s withdrawal reflex was measured with a stopwatch. This served as their thermal pain sensitivity measurement.
The behavioral tasks (emotional reactivity) consisted of a ‘novel object task’ using an object foreign to the dog (an interactive stuffed toy monkey!). The reasoning for this task was two-fold: to understand how a dog related to a novel object and to measure the latency of the dog’s approach to this novel object. Additionally, another behavioral task involved ‘the disgruntled stranger test’ which measured the dog’s response to a hooded stranger ‘speaking loudly over the phone and disregarding the dog.’ For the 2nd half of this measurement, ‘the stranger would remove their hoodie and greet the dog in a friendly tone of voice.’ Behavioral responses were recorded on video and analyzed.
Do veterinarians understand dog’s pain?
Interestingly, the veterinarians’ pain sensitivity ratings were directly related to all four QST results, although not all of the breeds were an exact match for the veterinarians’ assumption. In essence, a dog characterized with heightened pain sensitivity demonstrated a reduced pain sensitivity threshold, quantified by a diminished tolerance to mechanical QST in terms of force measured in grams, or a diminished latency to a thermal probe. In other words, our study proved the veterinarians’ belief regarding the pain sensitivity differences in the breeds, was shown to be correct. However, the veterinarians’ assumptions about specific breeds were not entirely in line with the findings of this study. The breeds that were the closest the veterinarians’ assumptions were the Golden Retriever, Labrador Retriever, and the Maltese.
The found distinctions in pain sensitivity thresholds among different breeds remained robust even when accounting for emotional reactivity and the feasibility of QST.
Although veterinarians' assessments of pain sensitivity did not provide significant insight into the detected breed variances in pain sensitivity among dogs, these ratings were positively correlated with the dogs' approach scores in the disgruntled stranger test. This implies that the initial interaction behavior of a dog with a stranger, specifically their initial greeting, could potentially influence veterinarians' evaluations of pain sensitivity across different dog breeds. It is interesting to note that even after considering emotional reactivity, variances in pain sensitivity thresholds persisted, suggesting that behavioral distinctions alone do not account for these findings.
In short, this study did determine that there are variations in pain sensitivity thresholds across dog breeds when measured through QST methods. Even so, these differences did not completely correspond to the breed-specific pain sensitivity beliefs reported by veterinarians.
Not that we didn’t already know that the veterinarians’ - and the dog owners’ assumptions about a dog’s pain levels (and therefore) response times are not always exactly on point.
Overcoming one’s pain, only if it’s really important!
Case in point, one of Medoc’s employee’s family dog. Its name was Munchie and Mutchie was a gentle, cuddly dog who lived a long a full life. We are, as you can tell from this piece, dog lovers. By the time Mutchie was 17 years old, he had, what the vet explained was, severe joint pain in all 4 legs. He was a very and greying man, grandfather-like in his personality. He would let us lift him up to his spot on the couch, carry him up the steps to get in and out of the house, etc. When he did walk, he was extremely slow. All movement seemed to be painful, difficult, and limited.
This being the case, when we decided to take Mutchie with us to visit some friends who raised birds, I didn’t think there would be any issues, as Mutchie couldn’t even get himself outside to do his business. Our friendly vet always seemed surprised when we brought Mutchie in for yet another checkup – he’d always say something like, ‘Hey Mutchie, you still around buddy?’
After the hour drive to our friends’ house, we were all excited to get out of the car. All of us, except Mutchie, who needed to be lifted out of the car and placed on the front steps. We weren’t inside for a full 5 minutes… one of the birds was flying freely around the living room. Suddenly, Mutchie, who can barely walk, jumps into the air, flies up to the couch and using the couch as a springboard, flies into the air, mouth open! Chomp! WHAT!!! How could this dog who could barely move, JUMP twice??? So much for our thoughts of how he would behave – not to mention our expert veterinarian. (no offense)
Yes, he caught the bird in his jaw. He didn’t get a chance to do any serious damage. We were all over him, prying his mouth open… but 17-year-old Mutchie FLEW!
Mutchie’s vet wasn’t wrong. Mutchie suffered from stiff joints and poor vision of old age. However, despite the pain of his later years, his hunter instincts overcame his suffering for a few seconds when he saw the bird flying around. All these years later, I am still amazed at Mutchies flight, and that he was able to match his jump to the bird’s flight pattern. Mutchie was indeed a special part of our family, complete with his behavioral intricacies and unexpected responses to stimuli.
QST aside, do we really understand pain in man’s best friend?
Any other dog lovers out there? We’d love to hear your stories about how your frail dog exceeded expectations and accomplished the impossible.
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