Fence-Line Interactions Among Farmed and Free-Ranging Cervids: Preliminary Results

Occurrences of disease outbreaks within and near captive cervid (mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni)) farms have recently drawn attention to these facilities. Some state wildlife and agricultural agencies have pondered making double fencing mandatory or otherwise increasing regulation of captive operations. Diseases such as Chronic Wasting Disease (CWD) and Bovine Tuberculosis (bovine TB) are a threat to captive and free-ranging cervid populations. Concerns over these and other diseases being transmitted from captive to wild cervids, and vice versa, have increased. In most cases, captive cervids are separated from wild cervid populations by a single fence, which could allow direct contact between populations through the fence. Transmission of CWD appears to be primarily from animal to animal (Williams and Young 1992, Spraker et al. 1997, Miller and Williams 2003, Miller and Wild 2004) and is likely density dependent (Peterson et al. 2002, Williams et al. 2002). Fence-line contact is believed to be a means of transmission of CWD between wild and free-ranging cervids (Miller and Thome 1993, Williams et al. 2002, Williams and Miller 2003). Fence-line contact is also a concern in the transmission of bovine TB (Rhyan et al. 1995), as the most common means of transmission being through inhalation (Sauter and Morris 1995, Palmer et al. 1999, Clifton-Hadley et al. 2001, Palmer et al. 2003)