Aiming to evaluate the prevalence of bone changes, radiographs were taken from both tarsal joints of 77 Crioulo yearlings, up to 26 months of age. The degree of changes was correlated with biometric parameters and management practices. The animals were separated into six groups, according to age: G1, including nine to 18 months old foals (34/77) and G2, with animals between 19 to 26 months of age (43/77); preparation time to halter class shows: GC, including animals who were not submitted to any preparation (29/77), and GI, consisting of young horses prepared to participate (average of 4.55 months of preparation time) in halter shows (48/77); and gender: colts (46/77) and fillies (31/77). Data were obtained from 24 breeding farms or training centers in Rio Grande do Sul state. Results showed that 79.22% (61/77) of the animals presented some degree of radiographically visible lesions, being 80.4% of males, 77.4% of females, 77.3% in GC, 79.2% in GI, 86.7% in G1 and 76.7% in G2. The mean body weight of the 10 to 12 month old yearlings (G1) was 293.2kg, representing 71.3% of the breed's mature weight and that of the 19 to 26 month old (G2) animals was 360.5kg (87.6% of the mature weight). The mean body weight of the GC was 288.9kg (70.2% of the mature weight) and of GI was 341.9kg (83.1% of the mature weight), although the average age of both groups was 16.8 and 19.0 months, respectively. A significant relationship was found between the animal's body condition score (P=0.01; r=0.3), time of preparation to halter class shows (P=0.0001; r=0.7), and neck crest score (P=0.02; r=0.3), and degree of the radiographic lesions found in the tarsi. Several factors can be involved in the development of distal tarsal juvenile osteoarthritis; however, in Crioulo breeding farms, the most important factor present was the horse's overweight.
juvenile osteoarthritis; overweight; developmental orthopaedic disease; degenerative joint disease