Abstract

In 2005, the Alaska SeaLife Center (ASLC) acquired a weaned, female harbor seal pup from Prince William Sound, Alaska, as part of a longitudinal research study. At capture, she was healthy but small and was hypothesized to have weaned early. Over two years, she developed health problems and unusual behaviors leading to retirement from research. Issues included strong food preferences, nervous disposition, and aerophagia, gastrointestinal distress (foamy diarrhea, regurgitation, vomiting, anorexia), poor weight gain, and elevated serum and fecal cortisol. Serial endoscopic examinations revealed intermittent, mild gastroenteritis. Histopathological examination of mucosal biopsies revealed varying degrees of lymphoplasmacytic, eosinophilic, neutrophilic, and catarrhal gastritis and colitis/proctitis consistent with parasitism, or bacterial or antigenic stimulation. Diet was altered to omit food items which appeared to cause the most distress. Contrast radiography revealed megaesophagus. She was maintained on small feeds of sardines and pollock and treated with simethicone to reduce bloat, lactobacillus to minimize bacterial overgrowth, and metoclopramide as a motility modifier. Gastrointestinal distress has been greatly reduced but intermittent bloating occurs.

Megaesophagus was also noted in rehabilitating harbor seals in 2009. It was a contributing cause of death of one pup that frequently regurgitated its feeds. Contrast radiography performed on eight additional pups showed four had varying degrees of esophageal dilation. One was euthanized due to severity of digestive symptoms. The remaining three were largely subclinical and were treated with motility modifiers and diet management, weaned successfully, gained weight, and were released.

Megaesophagus in a harbor seal was first reported in 1978 (Stroud) and has previously been found radiographically in another rehabilitating harbor seal pup and at necropsy in an adult captive harbor seal previously held at ASLC. The cause of megaesophagus in these cases and the implications for harbor seal populations are unknown.

Reference

1.  Stroud RK 1978. Esophageal dilation in a Harbor seal. J Zoo Animal Medicine 9(1):20-22.