Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2004
Publication Date: 9/20/2004
Citation: Pound, J.M., Miller, J.A., Oehler, D.D. 2004. Depletion rate of doramectin from blood serum of penned female white-tailed deer (Artiodactyla: Cervidae). Journal of Medical Entomology. 44(5):942-945.
Interpretive Summary: Although white-tailed deer are only marginal hosts for cattle fever ticks that transmit agents that may cause fatal diseases in cattle, they are the main hosts for ticks that transmit agents that cause Lyme disease, human ehrlichiosis, and other diseases in humans. Field trials have demonstrated that populations of these ticks can be greatly reduced by feeding the deer small amounts of corn coated with compounds such as doramectin that prevent the ticks from completing feeding. However, because these compounds are present in deer that may be hunted and consumed by humans, and because they currently are not allowed to be consumed by humans in the U.S., we need to know how much time it takes for them to be depleted from the venison after treatment. We treated deer with one of these compounds, doramectin, by allowing the deer to feed on corn coated with the doramectin. After treating the deer, blood serum samples were taken and analyzed at 3 and 4 day intervals to determine how quickly the compound was depleted from the serum. Concentrations of less than the minimally detectable 2 parts per billion (ppb) were observed within 14 days after treatment. Although depletion rates will need to be established for other tissues, this study establishes a baseline depletion rate of doramectin in blood serum of deer, and should aid efforts of the FDA to establish a withdrawal time for doramectin from white-tailed deer. This will and allow use of this technology in reducing the risk of cattle fever and other debilitating and potentially fatal diseases that are transmitted to humans, livestock, and wildlife as a result of being bitten by ticks.
Technical Abstract: Female white-tailed deer, Odocoileus virginianus (Zimmermann) were held in small pens and administered doramectin by free choice of doramectin-coated whole kernel corn and 19% protein deer pellets. Treated corn, pellets and water were fed ad libitum in separate containers. Blood serum samples that were taken from the deer before, on, and at 3 and 4 day intervals after termination of treatments were analyzed by HPLC to reveal the depletion rate of the parasiticide from blood serum. The mean doramectin serum concentration of 72.8 parts per billion (ppb) decreased to less than the detectable 2 ppb in all deer by Day 14 after termination of treatment.