Age- and sex-related changes in body weights and clinical pathology analytes in cynomolgus monkeys (Macaca Fascicularis) of Mauritius origin

Background: Clinical pathology and body weight information for the cynomolgus monkey in the literature is primarily derived from a small number of animals with limited age ranges, varying geographic origins, and mixed genders.

Objectives: This study aimed to summarize the age- and sex-related changes in clinical pathology analytes and body weights in cynomolgus monkeys of Mauritian origin.

Methods: Pre-study age and body weight data were reviewed in 1819 animals, and pre-study hematologic, coagulation, and serum biochemical analytes were reviewed in 1664 animals.

Results: Body weights were statistically higher (P < 0.01) in males than females in all age groups (2-10 years). These measurements became prominent after 4 years of age and peaked at 7 to 8 years of age in both sexes. Sex-related differences were noted in reticulocyte (RETIC) counts, creatinine, cholesterol, and triglyceride concentrations, and alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) activities. Age-related differences were noted in RETIC and lymphocyte counts, creatinine, triglyceride, phosphorus, and globulin concentrations, and ALP and GGT activities. The youngest (2 to <3 year) age group had the fewest number of clinical pathologic analyte differences including ALP and GGT activity differences which occurred in all age groups from 2 to 10 years; they also had age-related lower globulin concentrations. There were no age- or sex-related differences in coagulation measurands.

Conclusions: Sexual dimorphism in body weight was apparent for all ages from 2 to 10 years of age. The only difference in clinical pathology analytes unique to the 2 to <3 years of age group were age-related lower globulin levels.