The effects of sex and aging on selected plasma biochemistry analytes in zoo-kept American flamingos (Phoenicopterus ruber)

American flamingos (Phoenicopterus ruber) are commonly kept in zoological collections and are important in research, conservation awareness, and education. Hematology and biochemistry parameters are reported to change with age in many long-lived species. A retrospective analysis of recorded data (147 samples of PCV/TS and plasma biochemistry) from n = 16 (F = 7, M = 9) zoo-kept flamingos (1–16 years) was performed. Blood samples were collected as part of routine annual health evaluation over the course of 11 years. The effect of aging and sex on biochemical analytes in individuals over time was assessed. Most analytes did not differ between sexes. Males had higher TS, and lower sodium, chloride, and ALT concentrations when controlling for age. The only variable with a significant sex × age interaction was ALP, which only changed with age in females. Most analytes did not differ with age. PCV, UN, and Na:K ratio increased, while potassium, ALP, and uric acid concentrations decreased with each year of life. While aging influenced select biomarkers in the current study, the clinical significance has yet to be determined, and further studies including a larger age range are recommended.