Hematology and Blood Chemistry Reference Intervals for Antillean Manatees (Trichechus manatus manatus) in Colombia

Hematology and blood chemistry tests constitute easy-to-apply veterinary tool that evaluates an organism's systemic functioning and disease process by comparing the level of specific analytes against species norms. Such analyses help monitor marine mammals' health and nutritional status. Although reference values have been published for a few manatee populations, there are none for Antillean manatees (Trichechus manatus manatus) in Colombia. We aim to establish the reference values for hematology and serum chemistries for these manatees and determine if there are variations between individuals of different age groups and sex. Thus, we obtained whole blood and serum samples from 45 rehabilitated manatees from Colombia between 1992 and 2021. Complete Blood Count and Comprehensive Metabolic Panel values were calculated, and differences between age groups and sex were determined. Results were compared with published reference intervals of other Antillean manatee populations, Florida manatees (Trichechus manatus latirostris), and Amazonian manatees (Trichechus inunguis) from Brazil. We determined the reference intervals of hematology and serum chemistry for manatees in Colombia for different age and sex categories. No relevant clinical variations were found in hematological parameters due to sex. Marked differences were found between age groups, mainly among young animals with an expected faster metabolism. There were significant variations between hematological and blood chemistry values when the Colombian manatees were compared to manatees from Puerto Rico and Amazonian manatees from Brazil. Such variations are likely influenced by evolutionary history and environmental factors associated with differences in habitat salinity and diet. We recommend that future studies correlate these blood tests with specific panels. We further recommend conducting wild manatee health assessments as this information will yield essential data for species management schemes needed due to the multiple anthropogenic and environmental threats that manatees face today which put the Colombian manatee's health and ultimate survival at risk.