Septic Arthritis/Osteomyelitis May Lead to Osteochondrosis-Like Lesions in Foals

• Published in: Veterinary pathology Vol. 55; no. 5; pp. 693 - 702
• Main Authors: Wormstrand, Bjørn, Østevik, Liv, Ekman, Stina, Olstad, Kristin
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.09.2018
• Subjects: Pathobiology; Patobiologi; septic arthritis; bacteria; foal; histology; cartilage canals; growth cartilage; osteochondral lesions
• ISSN: 0300-9858; 1544-2217; 1544-2217
• DOI: 10.1177/0300985818777786

Failure of the cartilage canal blood supply leads to ischemic chondronecrosis which causes osteochondrosis, and osteochondral lesions. Osteochondrosis is a disease with a heritable component and usually occurs under aseptic conditions. Because bacteria can bind to growth cartilage and disrupt the blood supply in pigs and chickens, we considered whether this might play a role in development of equine osteochondrosis. The aim of this study was to examine whether bacteria are present in canals in the growth cartilage of foals with septic arthritis/osteomyelitis, and whether this is associated with osteochondrosis. The material consisted of 7 foals aged 9-117 days euthanized because of septic arthritis/osteomyelitis. The 7 cases had 16 lesions in growth cartilage that were evaluated histologically. Bacteria were present in cartilage canals in foals with septic arthritis/osteomyelitis. Portions of necrotic canals adjacent to bacteria frequently contained neutrophils, termed acute septic canals; or granulation tissue with neutrophils, termed chronic septic canals. Acute and chronic septic canals were associated with ischemic chondronecrosis in the articular-epiphyseal cartilage complex (AECC) of 5 cases and in the physis of 2 cases, and ossification was focally delayed in 5 of those 7 cases. Lesions occurred with and without adjacent osteomyelitis. Bacteria were present in cartilage canals and were associated with focal chondronecrosis in both the AECC and the physis. This establishes sepsis as a plausible cause of some osteochondral lesions in horses. It is recommended that horses with sepsis-related osteochondral lesions may be used for breeding without increasing the prevalence of OCD-predisposing genes in the population.