Fahrenholz Isabella C, Dennis Michelle M, Morandi Federica, Dittmer Keren E, Sheldon Julie D
Department of Small Animal Clinical Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996, USA.
Department of Biomedical and Diagnostic Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996, USA.
Animals (Basel). 2024 Jul 17;14(14):2088. doi: 10.3390/ani14142088.
Severe musculoskeletal disease characterized by marked joint laxity was the cause of euthanasia in two wild juvenile American black bears () 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 a 14-month-old emaciated male yearling exhibiting joint laxity and immobility. Necropsy findings showed osteoporosis and serous atrophy of 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.
2023年，两只野生幼年美国黑熊（）因严重的肌肉骨骼疾病被送往田纳西州东部的一家康复机构，该病以明显的关节松弛为特征，最终导致了它们的安乐死。此前，该种群中几乎所有报告的肌肉骨骼疾病均由创伤性病因引起，即使是营养不良的一岁幼崽也是如此。病例1是一只11个月大的孤儿雄性幼崽，表现出不成比例的侏儒症、进行性行动不便和关节松弛。尸检结果提示软骨发育异常或佝偻病，影像学检查结果支持骨骼发育不良。病例2是一只14个月大的瘦弱雄性一岁幼崽，表现出关节松弛和行动不便。尸检结果显示骨质疏松和脂肪浆液性萎缩，影像学检查结果与骨骼发育不良不一致。基于正常的钙、磷和甲状旁腺激素浓度，这两个病例在临床上均与佝偻病不符；然而，与健康的幼年黑熊相比，病例1存在维生素D缺乏症（9 nmol/L）。我们推测病例1患有遗传性软骨发育异常，而病例2的骨质疏松是由于慢性营养不良所致。本病例报告的目的是告知野生动物机构和设施，要监测自由放养熊类中类似的、与创伤无关的使人衰弱的肌肉骨骼疾病，并对相关病例进行评估，以便我们进一步了解其中涉及的疾病过程。
