Brain Abscesses in White-tailed Deer

Intracranial abscesses have been reported as a cause of natural mortality among male white-tailed deer across portions of the United States and Canada.  However, little is known about the prevalence and etiology of this mortality agent.  Pathology records of whitetails submitted to the Southeastern Cooperative Wildlife Disease reported intracranial abscessation in 24 of 683 (4%) deer.  Most (88%) cases occurred in males, with highest prevalence in older males.  Intracranial abscesses accounted for 20% of the diagnoses among 56 bucks >3 years old.   Subsequently, it was reported that 9% of 119 male skulls from deer found dead in the southeastern US had lesions characteristic of intracranial abscesses, whereas none of the 299 males examined from Texas had characteristic lesions.   Other reports of the prevalence of intracranial abscesses include 35% of known-fate mature male deer necropsied from Maryland.  In a sample of 170 Key deer of mixed sex and ages submitted for necropsy,  neurologic disease caused by intracranial abscesses was found in 17 adult males.

Because of the high variability in prevalence rates reported among the few studies conducted to date, as well as the purported impacts of climatic and demographic conditions on the prevalence of this disease, the impacts of cranial abscesses on white-tailed population demographics across Georgia is speculative.  Anecdotal observations suggest that prevalence may vary across physiographic regions, and may likewise be greater in herds managed to increase the occurrence of mature males in the population.  If intracranial abscesses are additive to natural and harvest mortality, in managed populations, it could be a significant impediment to the success of management efforts.

Further, most studies that have evaluated the prevalence of this disease have estimated prevalence among observed mortalities.  However, an unknown percentage of individuals with purulent infections may recover, albeit with varying degrees of necrosis and erosion of the frontal bones and antler pedicel.  This antler/pedicel damage often results in malformation of subsequent antlers, significantly reducing the trophy value of harvested animals.  Therefore, field evaluations of the prevalence of intracranial abscesses among geographically and demographically differentiated herds is warranted.

Principle investigators: Bradley Cohen and Emily Belser

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