Growth Plate Lesions of Fattening Bulls.

ABSTRACT

Lameness related to growth plate lesions is an important problem in the beef industry. This article describes the macroscopic and microscopic lesions in the distal metatarsal physis of bulls from an association of farmers in northeastern Italy. The metatarsal bones of 62 bulls (12 with severe lameness and 50 without lameness), average age 16.44 ± 1.72 months, were examined at the abattoir. The animals came from the same geographic area and shared intensive husbandry practices and a diet based on maize starch. A total of 124 metatarsal bones were sectioned, and the distal metaphyseal growth plate was grossly examined. Twenty-three cases, including 12 lame and 9 nonlame animals with visible lesions on macroscopic examination, and 2 controls (a total of 46 physes) were examined microscopically. Eight of 12 bulls with severe lameness had a chronic purulent physitis in at least 1 limb. Segmental thickening of the hypertrophic zone, consistent with osteochondrosis (OC), was present contralaterally ( n = 3 cases) and bilaterally ( n = 3 cases) in 6 of these animals. In the group of nonlame bulls, 19 of 50 (38%) had similar segmental thickening of the physis consistent with OC. In the remaining bulls, minor findings included partial closure of the physis and a variable degree of metaphyseal hyperemia. A high incidence of OC was found in both lame and nonlame fattening bulls. It is likely that lame animals were clinically more severe due to secondary hematogenous implantation of bacteria, resulting in a purulent physitis and severe lameness that required emergency slaughter in some cases.