The effects of copper supplementation on the prevalence of cartilage lesions in foals.

Summary The potential role of dietary copper in the development of cartilage defects in foals was investigated. Twenty-one mares were fed rations containing 13 ppm copper (CuC, control) or 32 ppm copper (CuS, supplemented) during the last three to six months of gestation and first three months of lactation. Their foals were fed pelleted concentrate containing 15 or 55 ppm Cu and were destroyed at 90 (5 CuC and 5 CuS foals) or 180 (6 CuC and 5 CuS foals) days. Focal cartilage lesions were found at multiple sites on necropsy. In foals killed at 90 days, there were over twice (9 versus 4) as many lesions of osteochondrosis and more than four times (9 versus 2) as many articular lesions of osteophyte formation or thinning in CuC foals compared with CuS foals. These differences were due predominantly to a higher number of lesions in one CuC foal. Two 90-day CuC foals had osteochondrosis of articular-epiphyseal (A-E) complex, one with thickenings and separation from subchondral bone and one with subchondral fibrosis. One 90-day CuS foal had a cartilage thickening of the A-E complex in the tibiotarsal joint with separation from subchondral bone. In foals killed at 180 days, there were seven times more articular lesions (21 versus 3) of osteophyte formation or thinning, nearly twice as many lesions of osteochondrosis (13 versus 7) in the physis and over five times as many involving the A-E complex (11 versus 2) in six CuC foals compared with five CuS foals. Thirteen lesions of osteochondrosis in the A-E complex had separation of the thickened cartilage from the subchondral bone, with nine exhibiting subchondral fibrosis. These were observed in 180-day CuC foals only. Lesions of osteochondrosis with separation of cartilage from subchondral bone were not observed in CuS foals. Supplementation of dietary copper to mares during late stage pregnancy and to their foals from 90 to 180 days of age appears to reduce the prevalence and severity of osteochondrosis and other developmental cartilage lesions in the foals, compared with foals and their dams fed slightly above National Research Council recommended levels.