MORBIDITY AND MORTALITY OF FREE-RANGING AMERICAN BLACK BEARS (URSUS AMERICANUS) UNDERGOING REHABILITATION IN EASTERN TENNESSEE, USA, 1996-2021

Debilitating Musculoskeletal Disease in Two Free-Ranging Juvenile American Black Bears (Ursus americanus)

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 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.

HEMATOLOGY AND PLASMA CHEMISTRY COMPARISONS AMONG JUVENILE AMERICAN BLACK BEARS (URSUS AMERICANUS) UNDERGOING REHABILITATION

The American black bear (Ursus americanus) is an opportunistic and adaptable species with high rehabilitation success rates. Injured, ill, and orphaned bears across the southeastern United States are examined and treated at the University of Tennessee College of Veterinary Medicine followed by rehabilitation at Appalachian Bear Rescue (ABR). Hematology and biochemistry reference ranges exist for healthy adult black bears; however, most bears presenting to ABR are young and of variable health status. Thus, further investigation into the difference of blood values at varying ages and presentations is warranted. ABR records from 1996 to 2022 included 106 bears with completed hematology and plasma biochemistry panels (22 paired samples at intake and release, 84 at intake only). Intake-only samples consisted of 12 neonates (<3 mon old), 64 cubs (3-12 mon), and 30 yearlings (1-2 yr). Bears presented as orphaned neonates (22%), orphaned cubs (45%), malnourished yearlings (24%), and injured/ill (9%) during fall (16%), winter (13%), spring (32%), and summer (39%). Changes in hematology and plasma biochemistry results between intake and release included an increase in hematocrit and glucose. Injured/ill bears presented with higher total leukocyte count (WBC), absolute neutrophils (ABS segs), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatine kinase (P < 0.05). Positive correlation between ALT, AST, proteins, and blood urea nitrogen and negative correlation between absolute lymphocytes and alkaline phosphatase were noted with age. Both WBC and ABS segs were lower during winter (P < 0.05). Understanding what factors affect juvenile black bear blood values improves clinical expectations and evaluation upon intake, clinical evaluation, and treatment.

Butorphanol-Azaperone-Medetomidine Is as Safe and Effective as Nalbuphine-Azaperone-Medetomidine for Immobilization of Juvenile American Black Bears (Ursus americanus)

Immobilization kits including butorphanol-azaperone-medetomidine (BAM) and nalbuphine-azaperone-medetomidine can provide effective, safe, and easy-to-use protocols in bears. Nalbuphine-azaperone-medetomidine is not commercially available but may be useful for wildlife agencies because it does not contain controlled substances. This study directly compared BAM to nalbuphine-azaperone-medetomidine immobilization in 10 juvenile healthy black bears (10 mo old; four females, six males) undergoing prerelease examinations after rehabilitation. Bears were immobilized via remote delivery of 1 mL of BAM (n=5) or nalbuphine-azaperone-medetomidine (n=5) intramuscularly in the shoulder during December (randomized, blinded trial). Bears were intubated, monitored with an electrocardiogram, pulse oximeter, capnograph, noninvasive blood pressure cuff, and rectal thermometer, and underwent physical examination, sample collection, morphometrics, and ear-tag placement. Induction, physiologic, and recovery parameters were recorded, including arterial blood gas analysis. The anesthetic agents were antagonized with atipamezole and naltrexone. There were no differences between protocols in induction or recovery times. There were no differences between protocols in heart rate, respiratory rate, temperature, oxygen saturation, end-tidal CO2, mean arterial pressure, or blood gas analysis or any differences between male and female bears in any parameters. Bears were hypertensive and normoxemic with low oxygen saturation via pulse oximeter, but all recovered smoothly and were released within 2 h of recovery. This study supports that nalbuphine-azaperone-medetomidine is clini-cally as safe and effective as BAM in American black bears.