Computed Tomographic Lesion Descriptors in Foals With Hematogenous Osteomyelitis: Interobserver Agreement and Association With Outcome.

Computed tomography (CT) is increasingly used to diagnose osteomyelitis in foals, but the prognostic value and interobserver reproducibility of specific CT lesion descriptors remain unclear. This multicenter retrospective study aimed to characterize CT features of hematogenous osteomyelitis in foals using a structured radiologic feature set, assess interobserver agreement, and evaluate associations between CT descriptors and survival to hospital discharge and long-term survival. We hypothesized that CT features considered aggressive, including a long transition zone, permeative or moth-eaten osteolysis, and discontinuous or irregular periosteal reaction, would be negatively associated with survival. Foals diagnosed with osteomyelitis and examined by CT at three tertiary referral centers were included. CT images were independently reviewed by three blinded observers. Interobserver agreement was assessed using Krippendorff's alpha. Associations between clinical variables, CT descriptors, and survival outcomes were evaluated using logistic regression. Fifty-six foals met inclusion criteria. Thirty-six foals (64%) survived to hospital discharge, and 26 of 32 foals (81%) with follow-up data survived long term. Articular involvement (p = 0.04; odds ratio [OR], 0.06; 95% confidence interval [CI], 0.04-0.89) and a long transition zone (p = 0.03; OR, 0.13; 95% CI, 0.23-0.78) were negatively associated with survival to discharge. Lesions at multiple locations were negatively associated with long-term survival (p = 0.03; OR, 0.05; 95% CI, 0.04-0.77). Interobserver agreement ranged from weak to moderate. Associations between individual CT descriptors and survival were limited, highlighting the need for prospective studies and improved standardization of CT lesion descriptors in foals with osteomyelitis.