June 2, 2016
More than three dozen wild horse advocacy groups have voiced their desire for federal authorities to make greater use of the fertility control vaccine PZP to manage America’s wild horses.
The organizations, which include the Humane Society of the United States, are said to represent more than 10 million people.
The groups contend that the PZP vaccine is a cost-effective alternative to roundups and removals of wild horses from the range – a federal strategy which has been widely condemned as expensive and ineffective.
However, contraceptive use has proved controversial among wild horse advocates, with some worried over their influence on herd dynamics and the health of the animals.
Today’s call for greater PZP use represents a major stand among groups advocating for better management of the mustangs that inhabit the vast western rangelands. They see it as a way to stave off the fiscal problems sparked by wild horse roundups, with an increasing share of the budget going toward the long-term care of the captive animals.
Neil Kornzse, the director of the Bureau of Land Management (BLM), the agency charged with managing America’s wild horses, admitted recently that the current system of roundups was failing. He said the agency’s policy of mustering and keeping the horses in facilities could potentially cost $US1 billion over the life-span of the horses.
Already, 70 percent of the BLM’s $US80 million Wild Horse and Burro Program budget was spent on roundups and removals, while less than 1 percent of that amount was spent on long available, humane and effective fertility control.
Groups supportive of the use of the PZP vaccine for humane wild horse management include the:
The BLM has removed more than 40,000 wild horses from public lands in the last seven years alone.
The National Academy of Sciences (NAS) recommended the use of PZP in its 2013 study, Using Science to Improve the BLM Wild Horse and Burro Program, saying it was “a more affordable option than continuing to remove horses to long-term holding facilities”.
The NAS study also noted that roundups and removals of wild horses were actually responsible for “facilitating high rates of population growth on the range”.
The NAS added that “removals are likely to keep the population at a size that maximizes population growth rates, which in turn maximizes the number of animals that must be removed through holding facilities”.
PZP is an immunocontraceptive vaccine. It works with a mare’s immune system to produce antibodies that block sperm receptor sites on the zona pellucida, a thin membrane surrounding the ovum.
Because it is non-hormonal, PZP does not :
The vaccine is reversible and is administered with a simple dart.
PZP has been used for more than 25 years in the wild horses on the Assateague Island National Seashore in Maryland. In that time, the herd has been brought to more sustainable numbers and the overall health of horses as a result has improved substantially.
In 1990, few horses on Assateague lived past 15 years. Now, many are living 30 years or more.
And, because PZP is not permanent, the National Park Service managers can closely control the herd’s population, allowing for increased births as appropriate.
Management programs with PZP have also helped curtail and even end roundups in wild horse management areas in the West, such as the Pryor Mountains on the Montana/Wyoming border, McCullough Peaks in Wyoming and Spring Creek Basin and Little Book Cliffs in Colorado.
In Colorado’s Spring Creek Basin, no mustangs have been removed since 2011, thanks to a BLM-facilitated public-private partnership using the PZP vaccine.
In addition, the BLM has committed to bait trapping if, in the future, the removal of some mustangs was necessary to maintain range health. Bait trapping is a far less traumatic capture method than helicopter roundups.
Increased use of PZP and a reduction in roundups and removals would also be a boon to US taxpayers, helping to curtail the cost of the existing program.
The public now spends about $US49,000 for each mustang that is removed from the range and not adopted. PZP, meanwhile, costs about $US27 per darted horse per year.
One economic model published in the Journal of Zoo and Wildlife Medicine showed that the BLM could save $US8 million over 12 years by using PZP in one herd management area alone. Multiply that by 179 HMAs and the cost-savings reach the hundreds of millions, according to the advocacy groups.