Seasonal variation in upper extremity cat bite injuries: implications for hand surgery workload and resource utilization

Abstract Background Cat bites constitute a significant and underrecognized source of upper extremity trauma, particularly in the domain of hand surgery. We aimed to characterize seasonal and demographic trends in feline-related upper extremity injuries presenting to the emergency department over 10 years, and to inform resource allocation, surgical workload, and injury prevention strategies. Methods We performed a retrospective observational cohort study of all emergency department visits for cat bites or scratches to the upper extremity within a large Midwestern health system from January 2014 to January 2024. Encounters were identified using ICD-10 diagnosis codes and merged with regional monthly climate data. Months were classified as warm (May–September) or cold (October–April). Hospital admission was used as a surrogate for clinically significant injury. Operative case data were extracted to characterize surgical burden, repeat washout rates, temporal trends, and sex-based differences in operative utilization. Results Cat bite presentations were significantly more frequent in warm months (74.6 ± 19.3) versus cold months (55.5 ± 14.3; p < 0.0001), with temperature explaining 26.3% of variance in monthly bite counts. Admission probability per bite was unchanged across seasons. Among 6,748 ED encounters, 235 operative cases (3.5% overall) were identified across 164 unique patients; the operative rate among admitted patients was approximately 37%. Forty-six patients (28.0% of operative patients) required multiple washouts, accounting for 117 of 235 total OR cases (49.8%). Operative volume did not differ significantly between warm and cold months ( p = 0.73). Annual operative volume increased from 10 cases in 2014 to 48 in 2023 (R² = 0.689, p = 0.003). Female patients comprised 73% of ED encounters but only 57.4% of operative cases ( p < 0.001). Conclusions Upper extremity cat bites peak in early summer correlating with warmer weather; injury severity and operative escalation rates remain stable across seasons. The high operative rate among admitted patients (~ 37%), concentration of operative burden among patients requiring multiple washouts, and a rising temporal trend in annual operative volume underscore the growing and disproportionate resource demands of complicated cat bite infections. Level of evidence Level III, risk / prognostic study.