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.