The Colorado Horse Development Authority (CHDA) recently announced the co-sponsorship of a study funded by Morris Animal Foundation on finding a fertility vaccine to help control wild horse populations. The research is being conducted at Colorado State University (CSU) in Fort Collins.

The mission of the CHDA is to promote and sustain the growth and development of the horse industry. By sponsoring an equine health study through Morris Animal Foundation, the Authority hopes to contribute to finding a safe, effective way for authorities to help control the wild horse population in the United States. .

There is widespread concern that overabundant free-range horse populations are altering natural plant communities and reducing forage areas for native wildlife and domestic livestock. Federal and state land management agencies have tried to reduce herds by periodically rounding up horses to adopt out or sell, but these efforts are seen by some as inadequate and expensive, and have resulted in injuries to both animals and humans. 

Controlling the fertility of free-range female horses could be more cost-effective and humane, but current contraceptives have limited effectiveness and can cause undesirable side effects. Researchers will administer a hormone contraceptive vaccine to induce infertility in female horses and will then evaluate its effect on reproductive and social behaviors in free-ranging horses. If results are positive, the contraceptive could provide a safe and effective tool for managing wild horses on public rangelands.