Incidence of Juvenile Osteochondral Conditions in Thoroughbred Weanlings in the South of Brazil

Abstract

The goal of this study was to determine the occurrence of juvenile osteochondral conditions (JOCCs) in Brazilian Thoroughbred weanlings from 4 to 6 months of age. Eighty-five foals from four different stud farms were evaluated. The history and husbandry of all animals were obtained by questionnaire, and clinical examination was performed to detect lameness. Radiographic evaluations included 24 radiographic projections from eight different joints (right and left metacarpophalangeal, metatarsophalangeal, tarsocrural, and femorotibial [FT] joints), for a total of 2,040 radiographs. Twenty locations within those joints were examined, and a severity index (SI) was determined for each location. The sum of the SI values for each foal was used to determine the osteoarticular status (OAS), which was classified as good, intermediate, or poor. None of the 85 foals examined had clinical signs of lameness. Sixty-five (76.5%) foals had one or more findings related to JOCC. In total, 680 joints were examined and scored, with 20.7% affected. The FT joints were the most commonly affected (n = 62; 9.1%). There was no significant difference in JOCC occurrence between the left and right limbs. The OAS was considered good in 38.8% (n = 33) of the foals studied, intermediate in 48.2% (n = 41), and poor in 12.9% (n = 11). There were significant differences in OAS among the four stud farms.