Evaluation of osteoarthritis in cats: novel information from a pilot study.

Objective: To describe structural changes associated with osteoarthritis (OA) in cats and to quantify OA-associated disability using functional evaluations. Study Design: Cross-sectional pilot study with longitudinal data. Animals: Normal cats (n = 2) and coxofemoral joint OA cats (n = 4) were evaluated by physical examination, radiography, and magnetic resonance imaging (MRI). Methods: Structural changes related to OA were scored using computed radiographs (CR) and MRI. Functional evaluation consisted of podobarometric gait analyses performed using a pressure-sensitive mattress and motor activity assessments using collar-attached, accelerometer-based activity sensors. Results: Structural scores for the coxofemoral joint OA-related lesions were lower in normal cats than OA cats for MRI (P = .07). Use of MRI allowed for whole-organ assessment of the coxofemoral joint. Pelvic limb peak vertical ground reaction force (PVF) was higher in normal cats than OA cats (P = .10). During the night, motor activity was greater in normal cats than OA cats (P = .04). PVF was positively correlated with mean motor activity (Spearman coefficient [Rho] = 0.83, P = .04) and negatively correlated with age and MRI structural score (Rho = -0.93 and -0.79, P < .01 and .06, respectively). Conclusions: This study provides the first description of OA-related lesions in cats using MRI. Gait analysis and accelerometry should be considered as objective tools to characterize OA-associated disability, although these assessments were weakly correlated with structural changes.