Hematology and serum biochemistry of free‐ranging mantled howler monkeys (Alouatta palliata) at La Pacifica, Costa Rica.

Background: Hematologic and blood biochemical values are key tools for assessing primate health. A long‐term behavioral study of howler monkeys at a single site (La Pacífica, Guanacaste, Costa Rica), afforded the opportunity to develop baseline values for a large group of animals, evaluating differences between adult males and females and comparing to a report in the same population two decades later. Methods: In 1998, 64 free‐ranging mantled howler monkeys were anesthetized and sampled for hematologic and biochemical analysis. Results: Blood analysis is reported for 29 adult females, 9 juvenile females, 19 adult males and 3 juvenile males. Four adults were excluded due to external injury or disease. There were few significant differences between adult females, juvenile females, and adult males. Conclusions: Baseline blood parameters are useful for determining normal values for howler monkey populations. The values for total protein, blood urea nitrogen, glucose, liver enzymes and potassium differed from a later study in 2019 may indicate changes that are influencing howler monkey health. [ABSTRACT FROM AUTHOR]