Comparison of blood parameters of ring-tailed lemurs (Lemur catta) and ruffed lemurs (Varecia variegata) under human care

Clinical monitoring is essential for disease prevention, both in an individual animal and even more in a captive animal population, where the susceptibility of different animal species in the same environment can lead to the onset of various pathologies. Periodic clinical monitoring must necessarily include an assessment of clinical status through a comprehensive physical examination, including body weight assessment and laboratory tests including fecal, urinary, and blood tests. The aim of this study was to monitor the health of a group of 45 lemurs (Lemur catta and Varecia variegata) in a zoo, focusing in particular on hematological and biochemical-clinical parameters obtained from blood samples collected annually over a three-year period. The hematological parameters measured were erythrocytes, packed cell volume, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, leukocytes, neutrophils, lymphocytes, eosinophils, monocytes, basophils, platelets, and mean platelet volume. The biochemical parameters measured were alkaline phosphatase, alanine aminotransferase, total bilirubin, glucose, amylase, lipase, cholesterol, albumin, globulin, A/G ratio, calcium, inorganic phosphate, total protein, creatinine, and urea. Observed parameters highlighted some differences between the two species over time and in relation to age. For example, red blood cell count consistently showed higher values ​​in V. variegata compared to L. catta. In Lemur catta, an increase in erythrocyte parameters, red blood cell distribution width and lipase was observed, compared to a decrease in mean corpuscular hemoglobin and bilirubin. Our results reveal a variation in hematological parameters in conjunction with the second blood sample with a greater increase in parameters in Varecia variegata than in Lemur catta. Results from this study partially disagree with those obtained in other lemur species kept in captivity and elsewhere. This would suggest that the management conditions, over three years, of the ring-tailed lemur and the variegated ruffed lemur at the zoo under study are particularly favorable, respecting the welfare of these animals.