Utility of Infrared Thermography in Dogs with Osteoarthritis

Objective, noninvasive biomarkers of joint inflammation or pain are needed for dogs with osteoarthritis (OA). This prospective, observational study investigated whether body surface temperature quantified by infrared thermography was associated with joint pain and/or radiographic osteoarthritis (rOA) in dogs. Using thermal images, 14 regions of interest (ROI) were created for bilateral limb joints and the vertebral column for each dog and the mean temperature was calculated for each ROI. Orthopedic examination and radiographs classified each joint/region as affected or unaffected by rOA, pain, or both, called symptomatic OA (sxOA). Mean temperatures were compared between affected and unaffected joints. Eighteen dogs were enrolled, encompassing analysis of 250 ROI (rOA = 83/250, 33%; pain = 83/250, 33%; sxOA = 61/250, 24%). No temperature differences were detected between affected and unaffected joints for rOA (0.405 °C, 95% CI [-0.204, 1.025 °C]), pain (0.208 °C, 95% CI [-0.390, 0.806 °C]), or sxOA (0.276 °C, 95% CI [-0.344, 0.915 °C]). Elbow and stifle regions were warmer, and the lumbosacral region was cooler than the carpus. Long-haired dogs were cooler than short-coated dogs. Regional temperature variability and haircoat type might hinder detection of OA-related thermal signals. In dogs with OA, findings do not support infrared thermography as a standalone tool to identify affected joints.