Objectives: To identify a cohort of cats with clinical osteoarthritis and to report on the clinical signs, the frequency of joints affected and the possible aetiopathogenesis within this population.

Methods: Inclusion criteria for this prospective study were presence of historical evidence and/or clinical signs of osteoarthritis, together with radiographic evidence of osteoarthritis. Patients showed clinical improvement within four weeks of analgesic administration and were free from other disease processes, which might explain the clinical signs and/or their response to analgesia.

Results: Twenty‐eight cases were included in the cohort. The elbow (45 per cent) and the hip (38 per cent) were the most frequently affected joints. Seventy‐one per cent of cases had primary/idiopathic aetiology. Alterations in both the ability to jump (71 per cent) and the height (67 per cent) of jump (lifestyle changes) were the most frequent signs of disease. Sixty‐one per cent of owners felt that their pet had made a marked improvement following administration of an analgesic/anti‐inflammatory drug. There were statistically significant improvements in the ability to jump (P<0�001), the height of jump (P<0�001), lameness (P=0�03), stiff gait (P=0�04) and the activity level (P=0�02) when compared with the start and the end of the study period.

Clinical Significance: Osteoarthritis is a clinical problem in cats, but overt lameness is not the most common clinical feature.