• Metabolic hormone levels and immunocompetence of neonatal harbor seals (Phoca vitulina) in rehabilitation settings compared to wild harbor seal pups

      O'Neil, Danielle Renee (2005-08)
      Health of harbor seal pups in rehabilitation and in the wild were compared using two metabolic hormones (cortisol and total thyroxine, TT4), two cellular immunity components (lymphocytes and eosinophils) and morphometric measurements. Neonatal harbor seals in two rehabilitation facilities were compared to wild harbor seal pups. Permanently captive harbor seals housed at the Alaska SeaLife Center were also studied. High levels of cortisol at weaning suggest changes in the stress response may be due to diet adjustments in pups during rehabilitation. The lower cortisol concentrations post-weaning suggest that pups in rehabilitation had overcome the challenge of pre-weaning diet, handling or environment and avoided chronic stress. TT4 concentrations were higher in wild pups, likely attributed to a more energetically demanding life in a dynamic environment. The rehabilitated pups showed lower lymphocyte counts and higher eosinophil counts compared to wild pups. Wild harbor seal pups were heavier and longer than post-weaned pups in rehabilitation. Animals in rehabilitation are possibly compromised at stranding, but it is also possible that current rehabilitation practices do not mimic what a healthy pup would receive from maternal investment, thus pups undergoing rehabilitation likely remain smaller and possibly immunologically compromised despite repeated and constant care in rehabilitation.