Observations on Spontaneous Stress-Related Mortality Among Males of the Dasyurid Marsupial Antechinus Stuartii Macleay.

Abstract

Splenic follicle sizes in male A. stuartii killed during the period of male mortality in 1973 were smaller than those of females killed at the same time. In 1974, all 17 males and two of four females held in the laboratory died during the period of male mortality in the field. Significant findings in some moribund animals included moderate anaemia, associated with heavy parasitaemias by Babesia sp. and elevated plasma corticosteroid levels. At autopsy, a high proportion of animals had haemoglobinuria, focal hepatic necrosis, and gastrointestinal haemorrhage due to gastric and duodenal ulcers. Males dying spontaneously had severely involuted splenic follicles. Listeria monocytogenes was recovered from four livers with focal necrosis but not from six livers with no necrotic foci. Splenic follicles were smaller in one group of males treated experimentally with a high level of exogenous corticosteroid. Deaths were related mainly to gastrointestinal haemorrhage, listeriosis and possibly babesiosis, considered to be associated with an adrenocortical response to stress, and concomitant reduction in resistance to infec- tion or latent disease. The probability that this syndrome is involved in mortality in the field is discussed.