Researching Deer Hair Loss Syndrome

Fawn showing signs of hair loss

Fawn showing signs of hair loss. Photo taken by DFG Biologist David Lancaster, Humboldt County.

A deer Hair Loss Syndrome (HLS) workshop was hosted by the Wildlife Investigations Lab on Aug. 20-21, 2012.  Most of the state’s leading researchers on HLS participated, including 17 wildlife veterinarians, epidemiologists, graduate students, veterinary pathologists and DFG environmental scientists. Participants reviewed current knowledge and status of research, identified priority research needs, and explored feasible management actions to mitigate the effects of HLS.

HLS is a recently described disorder affecting black-tailed deer in the coastal areas of Washington, Oregon and California. Little is known about the cause of the syndrome and its effect on black-tailed deer populations.  It is characterized by a severe infestation of an exotic chewing louse (Damalinia sp.), general decline in body condition, hair loss (especially over the thorax, flanks and hindquarters), morbidity, mortality and excessive grooming behavior. It is seen in mostly young deer, especially does, and is most evident in the winter and spring.

In 2009 another exotic louse species, Bovicola tibialis, was identified in California mule deer in Tuolumne County, causing a similar hair loss syndrome. Fallow deer are the natural host for B. tibialis.  How this exotic louse species adapted to native deer is unknown.

Dr. Pamela Swift, WIL wildlife veterinarian specializing in deer health, is the lead investigator of a HLS study, Statewide Assessment of Disease and Environmental Factors Affecting Deer Herd Population Demographics and Health, in which heavy metals (e.g., copper and selenium) in the deer are studied and compared to the presence of the exotic louse, and the presence of clinical hair loss. Samples collected from deer in the study are also analyzed and tested for a disease agent which could cause the suppression of the immune system leading to a severe infestation of lice.

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