Investigating the Probability of Response Bias in Owner-Perceived Pain Assessment in Dogs With Osteoarthritis.

Owners' ability to recognize signs of chronic pain in dogs undergoing pharmacologic and nonpharmacologic pain interventions during a period of physical rehabilitation is not known. This study aimed to compare dogs with and without chronic pain, and to assess the relationship between explanatory factors, including the probability of owners' response bias induced by pharmacologic and nonpharmacologic pain intervention, and chronic pain in dogs with osteoarthritis (OA). Seventy-one dogs with OA were included in this observational study. Owner-perceived pain interference was measured by Canine Brief Pain Inventory (CBPI) and owner-perceived pain behavior was assessed using Helsinki Chronic Pain Index. A dichotomous variable of Helsinki Chronic Pain Index was used in regression analysis to investigate the association between chronic pain and explanatory factors (body condition, anti-inflammatory medication, animal physiotherapy consultation once or more and owners' perception of pain interfering). Seventy-five percent of the dogs had ongoing anti-inflammatory medication, 51% of were overweight and 45% had a physiotherapy consultation. Higher levels of overt pain behaviors were reported in items addressing activities. Body condition, physiotherapy consultation and medication were not associated with chronic pain. Odds ratio (OR) and 95% confidence intervals of OR for the CBPI were 1.74 (1.23-2.47) and significantly associated with chronic pain. The adjusted OR of the CBPI did not differ from the crude OR. Owner-perceived pain behavior was not confounded by the dogs' medication. Results indicated that CBPI was not mediated by the medication. The CBPI pain interference score was not associated with response bias and may be used as clinical outcome measure of chronic pain and pain-related disability in dogs with OA along a period of physical rehabilitation comprising pharmacologic and nonpharmacologic pain interventions.