Blood chemistry reference intervals of captive Asiatic black bears (Ursus thibetanus)

Data on blood chemistry values can make fundamental contributions to our understanding of physiological changes. However, there is a lack of information regarding blood chemistry in Asiatic black bears (Ursus thibetanus). Thus, the objects of this study were to determine reference ranges for 29 blood chemistry variables, and to evaluate differences between age groups and between seasons. Blood samples (n = 138) were collected from 44 (20 males, 24 females; age range, 1–15 years) clinically healthy, captive Asiatic black bears (Ursus thibetanus) in the Republic of Korea. Young and adult bears showed significantly higher levels of creatinine and total cholesterol, and lower levels of blood urea nitrogen, blood urea nitrogen/creatinine ratio, lactate dehydrogenase and creatine kinase MB during hibernation compared to during non-hibernation. Adults also showed significantly higher levels of triglyceride, but lower levels of inorganic phosphorus, aspartate transaminase, alkaline phosphatase, high density lipoprotein cholesterol and creatine phosphokinase during hibernation than during non-hibernation. During hibernation, the urea nitrogen/creatinine ratio and levels of alkaline phosphatase, lactate dehydrogenase, and creatine phosphokinase in young bears were significantly higher than in adults, whereas creatinine levels were lower than in adults. During non-hibernation, the urea nitrogen/creatinine ratio and levels of calcium, alkaline phosphatase, lactate dehydrogenase, creatine phosphokinase and creatine kinase MB in young bears were significantly higher, whereas creatinine, total protein, albumin, gamma-glutamyl transferase and haemoglobin levels were lower than in adults. The results of this study provide reference values that will aid in understanding the physiology of Asiatic black bears and in assessing the health of these animals in captive environments.