Geographical Distribution and Prevalence of Hoof Disease in Southwestern Washington Elk Based on Hunter Surveys

Reports of lameness and deformed hooves in free-ranging Roosevelt elk (Cervus elaphus roosevelti) have occurred sporadically in southwest Washington for over a decade; however, the apparent number and geographical distribution of these reports increased dramatically in 2008. Informal surveys conducted by Washington Department of Fish and Wildlife (WDFW) staff during the winter of 2008-2009 revealed that up to 80% of observed herds in the area contained affected individuals. Within affected groups of elk, between 30-90% of the elk were lame or had deformed hooves, with a wide variation in the severity of individual cases. Both sexes and all age classes, including calves, appeared to be affected. Interviews with several large animal veterinarians who practice in the affected area did not reveal the existence of a similar condition in domestic livestock.

In March 2009, in collaboration with the Washington State University College of Veterinary Medicine, WDFW undertook a preliminary investigation to better characterize the hoof deformities being seen and to examine possible causes. Complete post-mortem examinations and ancillary diagnostic tests were performed on 5 elk from within the known affected area, and 3 apparently unaffected elk from a nearby area with no history of reports of lameness or hoof deformities. Necropsy, radiology, histopathology, bacterial culture, virus isolation, and parasitology were in all cases unremarkable and failed to indentify an underlying cause of hoof disease. Selenium and copper levels in liver tissue were severely deficient based on domestic livestock normal values (Han and Mansfield, 2009). It is not known whether the selenium and copper levels were abnormally low for elk in this area.

To gain a better understanding of the distribution and prevalence of hoof disease in southwestern Washington elk over time, during the summer of 2009 we surveyed hunters who had successfully harvested elk in the affected region during the preceding 10 years. We questioned them about their observations of groups of elk, as well as the elk they had harvested. Here, we report the findings from this survey.