Hind limb skeletal lesions in 12-month-old bulls of beef breeds

In the present study, right kind limb bones from 46 12-month-old bulls with no clinical signs were examined to identify and describe lesions that coul d predispose the stifle and tarsal joints to osteoarthritis. The Lulls came from a performance testing station and were slaughtered due to a low index at the end of thr testing period 1996-97. Differences in frequency of lesi ons among breeds as well as the relationship between lesions and growth rar e were evaluated. Forty-five (97.8 %) of the 46 bulls had lesions in the jo ints and/or growth plates. Prevalence of lesions was 100 % in the Charolais (22/22), the Hereford (8/8), and the Limousin (4/4) breeds, and 85.7 % (6/ 7) in the Simmental breed. The stifle was affected in 37, the tarsus in 33, and the growth plates in 34, of the 46 bulls. Lesions found in the stifle joint were: osteochondrosis of the articular-epiphyseal cartilage complex ( AECC) (25), subchondral bone cyst of the distal femur (1), fragmentation of the medial intercondylar eminence of the tibia (20), cleft in the distal p art of the patellar groove (28), and an avulsion fracture of the lateral co ndyle together with a partial tear of the cranial cruciate ligament (1). Le sions round in the tarsal joint were: osteochondrosis of the AECC (23), ulc erative lesions of the articular cartilage of the talus (25), and fracture of the medial malleolus (4). Twenty-eight bulls had lesions of osteochondro sis at the AECC and 37 at the growth plates. When osteochondrosis at the AE CC and thickening of the growth plates mere combined, 44 of the 46 bulls ha d at least one lesion at the AECC and/or the growth plate. Prevalence of bulls with at least one lesion was similar between breeds, bu t the number of lesions per bull was significantly higher in Charolais foll owed by Simmental, Hereford, and Limousin. Number of lesions per bull was s ignificantly correlated with daily weight gain, carcase weight, and the wid th of the proximal tibial epiphysis. Lesions were statistically independent , indicating that local biomechanical factors within the joints are importa nt in the pathogenesis. In conclusion, we suggest that the high incidence of hind limb osteoarthrit is reported in the Swedish beef bull population can be explained by the hig h prevalence of skeletal lesions found in the present material. The lesions appeared to be related to high growth rare and to the breed.