Hematologic parameters of captive lions (Panthera leo) and Siberian tigers (Panthera tigris altaica)

Background : The clinical evaluation of captive large felids has been a challenge for veterinarians and the diversity of management of this animals can complicate the standardization of hematologic parameters to these species. Red blood cells (RBC), white blood cells (WBC), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglo­bin (MCH), mean corpuscular hemoglobin concentration (MCHC) and platelet counts were measured, as well as plasma fibrinogen levels, from captive lions and Siberian tigers in Brazil. The objective of this study is to provide veterinarians an additional source of information concerning the reference values of hematologic parameters of lions and Siberian tigers. Materials, Methods & Results : This study presents the hematologic parameters of 29 captive lions ( Panthera leo ) and 16 captive Siberian tigers ( Panthera tigris altaica) from the Zoological Park of Sao Paulo Foundation. For inclusion in the experiment, animals were clinically examined, and those with recent physiological and/or concurrent alterations, those who were receiving any type of medication, those with an inadequate body condition score, those with dehydration, and those infested by ectoparasites or affected by some disease were excluded. The animals were chemically restrained on their own premises using anesthetic darts containing ketamine and xylazine. Blood samples were collected by jugular, cephalic or saphenous venipuncture. The appropriated volume intended for a hemogram evaluation was collected in tubes containing 2.7 nM Na 2 EDTA, to preserving the ideal ratio of blood to anticoagulant. For statistical analysis, Unpaired Student t tests were performed and P < 0.05 was considered statistically significant. No significant differences were found in the hematological values between male and female lions, except for the mature neutrophils values, which was higher in males. In Siberian tigers, the hemogram revealed significant differences between male and female counts for the number of leukocytes, mature neutrophils and lymphocytes. Leukocytes and mature neutrophils were higher in males whereas lymphocytes were higher in females. Discussion : Hematology is an efficient method for assessing the physiological status of individuals and often provides the first and only indicator of a disease. The results found are similar to what has been described in the literature. However, biological, methodological and analytical factors, along with their respective biases influence the hematological investi­gation of captive wild animals, and new reports may contribute to an expansion of the normal parameter ranges found by several authors. In this study, the three youngest of the 13 sampled Siberian tigers were approximately 11 months of age, and showed no differences in the evaluated clinical pathology values when compared with values from the adult Siberian tigers. Most likely, these three youngest Siberian tigers had already reached adult levels of the parameters investigated. Comparing the white blood cell values between male and female of lions and Siberian tigers, only tigers showed higher values of leukocytes in males (10.45 x 103/μL) than in females (7.37 x 103/μL), which may be explained by the reluctance of male Siberian tigers to being captured and higher levels of stress experienced by these individuals. This difference was attributed to females being better conditioned to the stress of capture, because they were more frequently handled for research projects.