Characterizing adrenocortical activity in zoo-housed southern three-banded armadillos (Tolypeutes matacus)

Improving the husbandry in the southern three-banded armadillo (Tolypeutes matacus) through gaining knowledge of its stress physiology is imperative to maintaining a healthy, zoo-housed population. Our objectives were to: 1) validate the use of fecal hormone analysis for monitoring adrenocortical activity using both an adrenocorticotropic hormone (ACTH) challenge and biological events; and 2) characterize longitudinal adrenocortical activity in male and female southern three-banded armadillos. An ACTH injection was given intra-muscularly to one male (4 IU/kg; 5.6 IU total) and one female (5.5 IU/kg; 8 IU total) southern three-banded armadillo. Fecal samples were collected 1 day pre- and continued 5 days post-ACTH to capture the physiological response measured by elevated fecal glucocorticoid metabolites (FGM) to validate these techniques. Additionally, natural and routine events, including pairing individuals for breeding and veterinary procedures/handling, were used to biologically validate these techniques. To characterize adrenocortical activity, fecal samples (∼3025 total; n = 275/animal/yr) were collected from 11 (5 males; 6 females) southern three-banded armadillos 5–7 times a week for 1 year at Lincoln Park Zoo (Chicago, IL). A cortisol enzyme immunoassay was used for FGM analysis. The ACTH challenge in the male resulted in a twofold increase of FGM (1123.2 ± 36.2 ng/g dry feces) above baseline (675.7 ± 10.0 ng/g dry feces) at approximately 54–94 h post- injection. The female exhibited a twofold increase (1635.4 ng/g dry feces) over baseline FGMs (608.5 ± 12.3 ng/g dry feces) approximately 30 h post-injection. Reproductive behaviors and veterinary procedures resulted in elevated FGM concentrations from all individuals except for one male. The longitudinal characterization demonstrated that sex and season did not influence (P < 0.05) FGM concentrations. Individuals were highly variable with mean FGM concentration of 2010.1 ± 862.4 ng/g dry feces (range, 816.3–7889.1 ng/g dry feces). Mean FGM baseline concentration was 878.5 ± 201.8 ng/g dry feces (range, 475.2–1955.5 ng/g dry feces) with a mean elevated FGM concentrations of 2694.3 ± 1111.4 ng/g dry feces (range, 1110.3–10,683.3 ng/g dry feces). This study provides the foundation for future research on how the environment directly affects the adrenocortical activity in this species of armadillo.

► Fecal hormone analysis validation to monitor adrenocortical activity in armadillo. ► Reproductive behaviors and veterinary procedures serve as biological validations. ► Fecal hormone analysis from 11 armadillos provided baseline data for this species. ► Sex, age, birth location and season had no effect on FGM concentrations.