Breed differences in pain sensitivity of dogs (#27)
Anecdotally breed may influence pain sensitivity in dogs. For example, the New Zealand huntaway, a farm working breed, is reported to be less sensitive to pain than other breeds, i.e. they are believed to have a high pain threshold. This, however, has never been scientifically tested. The aim of this study was to investigate differences in thermal nociceptive thresholds among dog breeds. Three New Zealand working/sport dog breeds (harrier hounds, greyhounds, huntaways, n=10 per breed) were used. To test thermal pain sensitivity, a progressively increasing heat stimulus was applied to the leg of each unrestrained dog using a remotely activated device, and the time and temperature at which the dog responded behaviourally was recorded. Each dog was tested 6 times in a one-hour session once a week for four consecutive weeks. Response time and temperature were analysed using a linear mixed model including fixed effects of device, breed, week, test and their interactions and dog as a random effect. A breed effect was found for latency to respond (raw mean ± SE (s): harriers 33.3 ± 0.9; greyhounds 34.6 ± 1.0; huntaways 36.4 ± 0.9; P = 0.003) and response temperature (harriers 49.0 ± 0.4 ºC; greyhounds 48.7 ± 0.4; huntaways 50.0 ± 0.4; P = 0.011). Huntaways took significantly longer to respond to the thermal stimulus than did greyhounds (P = 0.057) and harrier hounds (P = 0.0006) and responded at higher temperatures than the other breeds (greyhounds P = 0.0201; harrier hounds P = 0.0045). There were no differences in latency or response temperature between greyhounds and harriers. This study provides the first scientific evidence of breed differences in pain sensitivity in dogs, which can be valuable for developing tailored application of analgesics for dogs and for understanding differences in behaviour performance.