Sky Mountain Wild and Wildlife Immunocontraception
at Sky Mountain Wild Horse Sanctuary believe that the time is now for a
different vision for wild horses. Since the1971 passage of the Wild
Free-Roaming Horses and Burros Act, the primary means of “management”
for wild horses in the U.S. has been roundup and removal of mustangs
from their home range. Today in 2014, the Bureau of Land Management
(BLM) has over 50,000 wild horses in holding facilities, mustangs that
have forever lost their freedom through roundups. With an estimated
35,000 wild horses left roaming the western states on public lands, we
now have more mustangs in holding than we have free in the wild.
At Sky Mountain Wild, we realize our mission of engaging in humane,
science-based action to keep mustangs free in the wild through a unique
partnership with Mt. Taylor Mustangs and the Carson National
Forest. With our partners, we pioneered the first treatment of
mustangs on Forest Service lands in the U.S. with the immunocontraceptive Porcine Zona Pellucida, or PZP.
Treating mustangs with PZP means that wild horses remain free in the
wild in numbers that are healthy for them and for the range on which
they roam, as PZP safely limits reproduction. Sky Mountain Wild Horse
Sanctuary funded the cost of treating the first Carson mustangs to
receive PZP, and sanctuary co-founder Karen Herman and Mt. Taylor
Mustangs owner Dan Elkins darted these wild horses with the PZP. Today,
73 mustangs in the Carson Forest Jicarilla and Jarita Mesa Wild Horse
Territories have received PZP. These mustangs will keep their freedom,
and the initial cost savings resulting from keeping them wild instead
of rounding them up is conservatively calculated at $132,960.*
The additional savings resulting from limiting reproduction is $25,713
for foals that would have been rounded up and removed, for a total
initial cost savings of $158, 674. This savings is for the initial
costs of roundup and removal of wild horses, compliance, and preparing
each mustang for adoption. It does not include the additional savings
resulting from avoiding long-term holding costs for mustangs that would
have been transferred to holding facilities to live out the rest of
Today, Sky Mountain Wild continues to fund the Carson PZP Project and
to help treat mustangs with PZP in the wild, while providing a
life-long haven for the threatened mustangs we have adopted. We are
engaging in strategic planning to keep all Carson mustangs free by
using PZP to reach sustainable herd numbers, and to develop a model
that can be used for wild horses throughout the west.
Porcine Zona Pellucida (PZP):
What it Is, How it Works
wild horses with PZP to keep them free is a key aspect of Sky Mountain
Wild’s vision of mustangs living free and thriving in wild places. PZP
is an immunocontraceptive derived from pig ovum that vaccinates treated
mares against conception. Dr. Jay Kirkpatrick of the Science &
Conservation Center in Billings, Montana, pioneered the use of PZP for
wild horses. Mares are treated using a jab stick or remote delivery
with darts. Thereafter, mares may be treated once annually or every two
years to maintain immunocontraceptive effects, and the vaccination is
reversible up to seven years from treatment.
Twenty years of research demonstrates that PZP is:
90 % efficacy
has capacity to be delivered remotely
safe for pregnant mares
safe for mares’ health with long-term use
maintains wild horse family bands and social behaviors
does not pass through the food chain
The Carson National Forest PZP Project: The Beginning
March 11, 2009, mares from the Carson National Forest Jicarilla Wild
Horse Territory were treated with PZP. This marked the first time in
the nation that PZP had been used for mustangs from a U.S. Forest
Service Wild Horse Territory. Treating mustangs with PZP represents a
vast shift in the management of wild horses in New Mexico, as previous
management had been round-up and removal of wild horses from their
territories. Those first mares to receive PZP were gathered and brought
to short-term holding, where Dan Elkins and Karen Herman hand-injected
them with the PZP. Miraculously, no arms were broken in the process,
and the mustangs were released back into the wild. Dan has since
developed the means to dart mustangs out in the wild horse territories,
which eliminates stress for them and keeps them where they belong.
Carson PZP Team:
Dan Elkins, Owner, Mt. Taylor Mustangs.
is responsible for treating mares with PZP in the wild, and documenting
and tracking treated mustangs and their family bands.
Sherry Thompson, Executive Director, Thaw Charitable Trust – providing funding for the project.
Holly Hazzard, VP, US Humane Society – assisted with regulatory issues with FDA.
An article from the Santa Fe New Mexican on this project
savings is calculated using data provided by the Carson National Forest
on the cost per mustang for roundup, removal, and compliance, which in
2011 was $2571 per wild horse. Cost savings for foals is calculated
based on the $2571 cost per mustang with a 90% PZP efficacy and a 15%
annual rate of reproduction.