Intracranial abscessation as a natural mortality factor for adult male white-tailed deer (Odocoileus virginianus) in Kent County, Maryland, USA.

Intracranial abscessation is a cause of natural mortality among free-ranging white-tailed deer (Odocoileus virginianus) across portions of the United States and Canada. Intracranial abscesses caused by Arcanobacterium pyogenes disproportionately affect adult male white-tailed deer. From 2003-08, we evaluated the occurrence of intracranial abscessation among adult (> or = 2.5 yr) radiocollared male white-tailed deer (n=33) at a large private property in Kent County, Maryland, USA. We documented mortality and necropsied 26 (79%) of the 33 deer. In 2007, we collected swabs from the antler bases and nasopharyngeal membranes of living male white-tailed deer in Maryland, USA (n=9), and Texas, USA (n=10), and from freshly rubbed (n=7) and unrubbed (n=7) trees in Maryland, USA. Swabs were cultured for the presence or absence of A. pyogenes. In Maryland, USA, nine (35%) of the 26 necropsied radiocollared male deer had intracranial abscesses. Five (56%) of nine Maryland, USA, males, and none (0%) of 10 Texas, USA, males cultured positive for A. pyogenes. No rubbed or unrubbed trees at the Maryland site cultured positive for A. pyogenes. The rate of intracranial abscess among adult male white-tailed deer at the Maryland, USA, site (35%) exceeds reported rates for other regions of the United States (9%).