Since 1988, the wild horse population of Maryland’s Assateague Island has been successfully controlled using a contraceptive vaccine (PZP) developed with the help of the Humane Society of the United States. Dr. Jay Kirkpatrick is assisting the BLM in implementing this non-intrusive contraceptive method across a growing number of herd management areas.
The method has proven very successful, is easy to administer (via remote darting of the mares) and does not disrupt the complex social structure of wild herds. A March 2004 USGS study found that $7.7 million could be saved annually through the use of contraceptive measures alone.
PZP should be used judiciously, solely to the extent necessary to maintain healthy population levels, in keeping with the intent of the 1971 Act. The goal is to minimize the need for costly and traumatic round-ups as well as save millions of tax dollars, while ensuring genetic diversity.
Use of PZP is subject to oversight by the Humane Society of the United States. The government’s recent interest in alternative contraceptive methods that are not subject to HSUS oversight is of great concern to wild horse advocates. Uncertainty as to the safety and reversibility of some of these newer methods, such as the vaccine SpayVac, are also cause for concern.