On assessment methods related to pain in dogs with osteoarthritis

There is a need of valid and reliable assessment methods that are clinically applicable in canine rehabilitation practice. The aim of this thesis was to psychometrically evaluate measurement properties in assessment methods related to pain in naturally occurring canine osteoarthritis. Assessment methods developed for heart rate variability analysis, i.e. Polar heart rate monitor, and owner-reported perceptions of pain severity and pain interference with functionality, i.e. Canine Brief Pain Inventory, were tested. Methods: Four observational studies were conducted. Study I was a cross-sectional study consisting of two groups of consecutively recruited dogs. The Canine Brief Pain Inventory was administered to owners of dogs with naturally occurring osteoarthritis (n=61) and clinically sound dogs (n=21). Study II was a descriptive and correlative cross-sectional study based on the same sample of dogs with osteoarthritis (n=71), assessing chronic pain behavior and associations between explanatory variables and chronic pain behavior. Study III and IV were correlative studies, assessing Polar heart rate monitor measuring interbeat intervals and time- and frequency-based heart rate variability parameters, compared to simultaneously recorded electrocardiogram in dogs (n=11). Results: High internal consistencies and ability to discriminate sound dogs from osteoarthritis dogs were found. The hypothesis of the presented two-factor structure of the Canine Brief Pain Inventory was rejected. Owners reported higher proportions of chronic pain behavior in items targeting physical activities, e.g. getting up, moving after rest and moving after major exercise. A minor proportion of dogs with osteoarthritis showed no owner-perceived behavioural signs of chronic pain. Owner observations were not associated with ongoing antiinflammatory medications. In Study III and IV, 595 errors (12.3%) were identified in Polar data. The number of errors were unequally distributed among the dogs. Interbeat intervals and heart rate variability parameters from electrocardiogram and Polar were strongly associated. Standard error of measurements were high among some heart rate variability parameters in Polar and electrocardiogram. In conclusion, this thesis contributes to our knowledge about assessment methods related to diverse components of pain in dogs with osteoarthritis, allowing improved pain management in clinical practice