Increased glucocorticoids cause a characteristic stress leukogram in mammalian taxa. It is assumed that avians exhibit a similar response, but to date, there have been no controlled studies to correlate serial endogenous corticosterone levels to hematologic values. An established flock of 18 Hispaniolan Amazon parrots ( Amazona ventralis) was used as a model in a crossover study. The treatment group was subjected to the stress of transport, restraint, and common clinical procedures with serial blood samples collected at 20-min intervals for hematology and corticosterone levels; the control group was sampled at the same intervals. Longitudinal data analysis was performed with linear mixed modeling. For all hematologic analytes, the baseline value had a significant positive effect on subsequent values (all P < 0.001). The white blood cell, heterophil, and eosinophil counts and heterophil to lymphocyte ratio increased over time in the treatment group, whereas it remained stable in the control group ( P = 0.016, P < 0.001, P < 0.001, P = 0.02, respectively, for the time*treatment effect). Lymphocyte absolute counts decreased over time, although not significantly; the decrease was significant for the relative lymphocyte count in the treatment group. Monocytes and basophils were not significantly altered. The treatment group had a higher mean corticosterone level overall than the control group by approximately 60% ( P = 0.008). The mean corticosterone level also increased over time in both groups by three- to fourfold ( P < 0.001) by 20 min then plateaued. These results demonstrate that some significant hematologic changes may arise with routine handling and transportation of birds and should be accounted for in hematologic interpretation of cell counts.
Keywords: Amazona ventralis; Hispaniolan Amazon parrot; avian hematology; corticosterone; stress leukogram.