Bone infection in a wild capybara (Hydrochoerus hydrochaeris) from Northeastern Argentina: implications for population health monitoring.

Hydrochoerus hydrochaeris is the largest extant rodent in the world. It is an iconic mammal of the tropical and subtropical wetlands of South America, with significant importance in the ecosystems of northeastern Argentina. Although several diseases affecting capybaras in wild and in captivity have been reported-mainly of bacterial, metabolic, parasitic, and viral origin-bone pathologies remain undocumented. This study presents a macroscopic and radiological analysis of skeletal lesions observed in a road-killed capybara from Corrientes Province, Argentina. The specimen exhibited a marked lesion on the left hemimandible consistent with osteomyelitis, an acute infectious process of nonspecific origin. Extensive bone proliferation was also observed on the humerus, interpreted as enthesic origin, based on its association with forelimb musculature. Additionally, vertebral and tibial lesions were identified and attributed primarily to the individual's age, consistent with osteoarthritis and osteochondritis dissecans probably the result of subchondral fracture-induced vascular compromise. To our knowledge, this is the first report of these bone pathologies in H. hydrochaeris and underscores the value of systematic examination of carcasses to improve understanding of the health status of wild capybara populations.