Severe musculoskeletal disease characterized by marked joint laxity was the cause of euthanasia in two wild juvenile American black bears (Ursus americanus) admitted to a rehabilitation facility in eastern Tennessee in 2023.Previously, almost all reported musculoskeletal diseases in this population were of traumatic etiology, even in malnourished yearlings.Case 1 was an orphaned 11-month-old male cub exhibiting disproportionate dwarfism, progressive immobility, and joint laxity.Necropsy findings suggested either chondrodysplasia or rickets, and imaging findings supported a skeletal dysplasia.
Case 2 was Automotive relays a 14-month-old emaciated male yearling exhibiting joint laxity and immobility.Necropsy findings showed osteoporosis and serous atrophy of DVI-D Digital Video Cable fat, and imaging findings were inconsistent with a skeletal dysplasia.Both cases were clinically inconsistent with rickets based on normal calcium, phosphorous, and parathyroid hormone concentrations; however, Case 1 had hypovitaminosis D (9 nmol/L) compared to healthy juvenile black bears.We hypothesize that Case 1 had a genetic chondrodysplasia while the osteoporosis of Case 2 was due to chronic malnutrition.
The goal of this case report is to inform wildlife agencies and facilities to monitor for similar, non-trauma-related debilitating musculoskeletal disease in free-ranging bears and evaluate cases that allow us to further understand the disease processes involved.