Stress in wild-caught Eurasian otters (Lutra lutra): effects of a long-acting neuroleptic and time in captivity
As part of a translocation project, 28 Eurasian otters (Lutra lutra) were captured from the wild and transported to the Barcelona Zoo for veterinary evaluation, quarantine and intraperitoneal implantation of telemetry devices. Eleven animals were injected with the long-acting
neuroleptic (LAN) perphenazine enanthate at the time of capture and the remaining animals served as a control group. During their time in captivity, which averaged 23 days, all of the animals were bled three times. Haematological and biochemical parameters were evaluated, including red blood
cell count (RBC), haemoglobin (Hb), white blood cell count (WBC), blood urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), lactate dehydrogenase (LDH), creatine kinase (CK), albumin, and serum cortisol. No significant differences were found between
treated and control otters except for monocyte count, which was higher in treated animals. Time after capture had an effect on many parameters. RBC and Hb decreased at first and then increased, while WBC and segmented neutrophils decreased over time. Most of the biochemical parameters considered
to vary in relation to stress, including AST, ALT, CK, AP and LDH, decreased over time, suggesting that the stress responses of the animals decreased throughout the period of captivity. However, no significant change in serum cortisol levels was noted. The lack of effect of perphenazine treatment
on haematological parameters should encourage further research on other stress indicators applicable to wild animals, such as behaviour or faecal cortisol concentration. Finally, the results obtained in this study suggest that, when captive conditions are adequate, keeping wild-caught animals
in human care for a period of time prior to their release into the wild can be beneficial. However, further studies taking into account other welfare indicators would be useful.