Mechanisms of deaths in captive juvenile New Zealand fur seals (Arctocephalus forsteri)

Abstract

Juvenile seals are sometimes encountered in waters around South Australia with injuries and/or diseases that require veterinary treatment. Two cases are reported where apparently stable animals died soon after being rescued due to quite disparate conditions. In Case 1 a juvenile male New Zealand fur seal (Arctocephalus forsteri) was found unexpectedly dead in its enclosure. A necropsy examination revealed an emaciated juvenile male with no injuries. The intestine was filled throughout its length with melena stool that was due to heavy infestation of the stomach with roundworms with adjacent gastritis. Death was due to shock from upper gastrointestinal blood loss secondary to parasitosis. In Case 2 a second juvenile male New Zealand fur seal (Arctocephalus forsteri) also died unexpectedly in its enclosure. It had been listless with loud respirations since capture. At necropsy there was no blood around the head, neck or mouth, and no acute external injuries were identified. An area of induration was, however, present over the snout with fragmentation of underlying bones. The maxilla was freely mobile and CT scanning revealed multiple comminuted fractures of the adjacent facial skeleton. Examination of the defleshed skull showed fragmentation of the facial skeleton with roughening of bones in keeping with osteomyelitis. Death was attributed to sepsis from osteomyelitis of a comminuted midfacial fracture. These cases demonstrate two unusual and occult conditions that may be present in recently retrieved juvenile fur seals. Failure to establish the correct diagnosis rapidly may result in death soon after capture. The usefulness of imaging techniques such as CT scanning in delineating underlying injuries prior to necropsy is clearly demonstrated.