A synopsis of a presentation to veterinarians during The American Mustang session at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.
Feral tribal horses walk the streets within the Navajo Nation. They’re outside restaurants. In people’s yards. There are just too many horses, and the Navajo government is working to change that. It started in 2013 with community roundups and a veterinary management program.
Scott Bender, DVM, works as tribal veterinarian with the Navajo Nation Veterinary Program and is a USDA Animal and Plant Health Inspection Service consulting veterinarian. At the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah, Bender shared the challenges faced when managing feral horses within the Navajo Nation and results of tribal equine population management efforts.
The Navajo Nation is located in the southwestern United States, with territory spanning Arizona, Utah, and New Mexico. The reservation comprises 18 million acres and, said Bender, an estimated 75,000 to 96,000 horses.
The tribe permits 12,000 livestock owners, with the majority of permit holders having one to five privately owned horses.
Under tribal law, all unbranded horses within the Navajo Nation are tribal property, Bender explained. That leaves the tribe with a lot of horses.
The Navajo traditionally view horses as sport, working, and food animals. “The horse is sacred to the Navajo, but that doesn't mean we don't eat them," Bender explained. The Navajo believe horsemeat has medicinal, healing properties and is useful as a “winter” meat, he said, explaining that “horsemeat, by tradition, can only be eaten in the winter between October and April—end of thunder and not after ‘first thunder.’”
Initially and into the early 20th Century, the U.S. Bureau of Indian Affairs managed tribal livestock, but management has slowly transitioned to the sovereign nation government, Bender said. This happened partly because of U.S. government-approved reduction of livestock in the 1930s and the euthanasia and burial of more than 500 horses by federal authorizes following a dourine outbreak at the Canyon de Chelly National Monument, which is located in northeastern Arizona within the Navajo Nation boundaries. “This ‘waste of resources’ has left a negative indelible mark on the attitude of Navajo livestock owners toward the U.S. government,” Bender said.
To the Navajo, unused horsemeat is a wasted resource that the creator gave the people, he clarified.
With this in mind, surplus Navajo horses had historically been sold off-reservation to slaughter as a way to manage populations and produce income. When U.S. equine slaughter plants closed in 2007, the tribal horses lost 95% of their value and the surplus feral horses were left to breed without human controls, Bender said. “The current (tribal) horse issue is a direct result of the elimination of an outlet for surplus horses,” he added.
As herds grew, damage to rangelands increased, as did horse-caused human injuries. “Horses in right-of-ways caused car wrecks, human injuries, and even deaths,” Bender said. These issues led tribal communities to request that the Navajo National Department of Agriculture start its equine population management program in 2013, which involved roundups and veterinary services, including free:
While the initial fertility vaccination was effective, Bender described owner booster rates of horses as “dismal,” despite the program’s outreach and communications efforts promoting boosters. The program’s leadership is now investigating anti-gonadotropin-releasing hormone vaccine (know more commonly as anti-GnRH or GonaCon) use as a longer-activing and single-dose alternative to PZP.
In 2013 the Navajo Nation local communities, with the help of the Navajo Nation Departments of Agriculture and Resource Enforcement, rounded up more than 8,900 horses. Permitted owners claimed approximately 250 horses, with the tribe selling the rest with the requirement that they could not be returned to the Navajo Nation.
The veterinary program’s goal was to castrate 1,000 male horses and vaccinate 1,500 mares against fertility by the end of 2014. To date, more than 700 horses have been castrated or vaccinated with PZP for fertility control. Bender said members of communities where horse removals took place have reported improved forage conditions in spite of the continuing 14 years of drought in the southwestern United States and Navajo Nation.
Source: The Horse
The National Park Service (NPS) is currently studying the use of fertility control vaccines to control feral horse populations on NPS lands.
Jenny Powers, DVM, PhD, an NPS wildlife veterinarian, shared preliminary results during a presentation at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.
Managers at Theodore Roosevelt National Park in North Dakota are seeking ways to control feral horse populations that include alternatives to helicopter roundups and sales.
The horses, which some consider culturally significant and suggest are the origin of the Nokota breed, share the same range as elk, pronghorn, mule and white-tail deer, and bison in the 46,000-acre park, necessitating careful resource allocation and equine population management, Powers said.
In October 2009 NPS started a study using a gonadotropin-releasing hormone (GnRH) immunocontraceptive vaccine on mares in the park. First, park managers rounded up and removed half the park’s horses. They then blocked the remaining mature mares by age, body condition, and reproductive status. They separated the horses into a treatment group of 29 and a nontreatment group of 28 individual mares.
The treatment group received 2 mL of GnRH vaccine. The control group received 2 mL of saline. Most mares were pregnant at the time of treatment. “The GnRH vaccine we used showed promise as a multiyear vaccine after giving a single dose," Powers said. "This is highly unusual for a vaccine to work for more than a year and would greatly improve the efficiency over currently available fertility control vaccines.”
Over the next four years, NPS researchers observed the mares for:
In the first foaling season, 2010, researchers saw no statistical change in foaling or foal survival rates, as was expected because most animals were pregnant at the time of vaccination, and there was no difference in foal survival between treated and control mares, Powers said.
In the second foaling season (the first expected to be affected by vaccination), the proportion of treated mares that foaled was 35% less than untreated mares. The third foaling season saw the proportion of treated mares that foaled 30% less than untreated mares. But the fourth foaling season, researchers observed no statistical difference in foaling rates between treated and untreated mares.
NPS managers observed minimal changes to reproductive behaviors or time budgets, Powers said. Of the treated mares, 80% had injection site swelling one to four years after treatment.
Overall, NPS researchers found a single vaccination with the GnRH vaccine provided a modest decrease foaling rates for two years post-vaccination and had little effect on social behaviors, she said, adding that treated mares had no more or less reproductive interaction with stallions than untreated mares.
She also said treated mares did have apparent inflammatory reactions at injection site, but this did not appear to affect their well-being, as they did not become lame or lose body condition.
“The NPS is currently studying the efficacy of revaccination four years after the first vaccination, and researchers are interested in how long a booster vaccine might last and how effective it can be at preventing pregnancy,” Powers concluded.
Source: The Horse
Click Here to view white paper, presented at the AAEP conference
A group advocating for Alberta’s free-roaming horses has entered into an agreement with the province to “humanely manage” the population by starting both contraception and adoption programs.
The memorandum of understanding between Alberta Environment and Sustainable Resource Development and the Wild Horses of Alberta Society will allow the group to help manage horses in the Sundre area.
“It’s a five-year agreement,” said Duncan MacDonnell, spokesman for Alberta Environment. “The agreement allows Wild Horses of Alberta Society to undertake two experimental programs to help control the wild horse populations.” But it doesn’t necessarily preclude another capture season this spring, he said, noting that decision is still pending.
Provincial officials have maintained the horse population needs to be balanced with the health of the grasslands — a position that led to controversy last spring as the province allowed a six-week capture season for up to 196 horses that could be kept for personal use or sent for slaughter. Only 15 animals were rounded up by two ranchers, but it led to protests by wild horse advocates, who suggested there were fewer animals than the province reported.
The official 2014 count showed there were 880 horses in the foothills between Kananaskis Country and Sundre, down about 100 horses from the previous year. It led activists and conservationists to suggest last spring’s capture season was unnecessary.Throughout the debate, others suggested the province try other methods to manage the population.
The agreement between the province and the Wild Horses of Alberta Society includes a contraception program targeting female horses and an adoption program allowing the organization to take in and adopt out any young horses.
Bob Henderson, president of the society, couldn’t be reached for comment, but a news release issued by the group said it’s excited about the opportunity to help manage the horse population. It noted that the contraception program will select a limited number of mares to receive a vaccine to prevent pregnancy for up to three years without disrupting the herd structure and dynamics.
The adoption program will allow the group to take in any young foals that have been abandoned or injured. It also allows rescue of any horses that stray onto private land or roadways. The programs will all be run on donations from the public, including eight hectares of land, where a safe handling facility will be built.
Officials with the province said the Wild Horses of Alberta Society will be required to show results from both programs over the five-year period.
Source: Calgary Herald by Colette Derworiz
Is Wyoming waking up to the reality of our nation’s unworkable approach to managing wild horses? The horse issue is so heated and divisive, that I’m a natural skeptic.
However, the recent news that a group of Wyoming legislators is urging the U.S. Bureau of Land Management (BLM) to rethink its approach to horses makes me, at least, somewhat optimistic.
According to an Oct. 28 article in The Horse magazine, legislators also plan to work with Gov. Matt Mead’s office to educate Wyoming residents about horse management issues. Although this discussion is prompted more by land-use concerns than by wild horses, more dialogue is welcome.
Federally protected wild horses on public land have no intrinsic economic value, yet compete with the enormous economic interests of the livestock industry, mining, energy development, and recreational use.
According to financial data supplied by the BLM to the Wild Horse and Burro Advisory Board, the agency spent 67 percent of its total annual $77 million wild horse budget, in 2014, rounding up, removing and stockpiling horses from federal lands. It spent a mere 0.3 percent on population growth suppression for 450 mares. Three of five wild horses now live in government holding pens and pasturages, costing taxpayers an estimated $120,000 per day. Worse, each removal merely speeds up the reproductive success of horses remaining in the field.
Although BLM field censusing is not scientific, the agency claims there are 40,000 wild horses on federal lands that can sustain less than 30,000. With few natural predators, however, populations will grow. The federal government’s Wild Horse and Burro Adoption Program can place only a few thousand horses each year. There is no good outcome to the current situation until BLM starts to aggressively curb wild horse population increases.
One strategy that could help significantly is more widespread use of wildlife contraception, as advised by the National Academy of Sciences in 2013. The immunocontraceptive vaccine, native PZP, has a long track record of success in wild horses, dating back more than 25 years.
Today, native PZP vaccine is used in more than 20 Herd Management Areas (HMAs)—several in Wyoming. Model PZP programs at McCullough Peaks HMA, near Cody, and the Pryor Mountain Wild Horse Range, traversing the Wyoming/Montana border, have sharply reduced population growth. Little Book Cliffs Wild Horse Range, near Grand Junction, Colorado, has also demonstrated the value of fertility control.
This vaccine blocks fertilization in mares and other animals, such as bison, elephants and urban deer. It can be administered by a rifle-fired dart and doesn’t harm existing pregnancies or an animal’s health. Unlike earlier, hormone-based wildlife contraceptives, PZP breaks down in the mare’s body and will not pass into the surrounding environment, or to other horses. The vaccine is also reversible.
BLM has been studying contraceptive agents for years and is said to be holding out for a longer-lasting vaccine. Mares that receive native PZP need boosters every year for the first two-to-three years and then every-other or every third year. This presents challenges in large HMAs. However, horses can be gathered expressly for treatment in temporary corrals through bait or water trapping. That presents a minor challenge compared to the expense and man-hours required for humanely accommodating growing numbers of once-wild horses. Had more HMAs started using immunocontraception 15-plus years ago, as advised by the scientific community, horse populations would be far lower.
In some HMAs and wild horse ranges, volunteer groups have been trained to dart mares with native PZP and to track those requiring boosters. This is far less costly than paying more and more to round up, feed and care for these animals off the range. Caring for a horse over a 30-year life span costs taxpayers around $45,000, compared to well under $1,000 to gather, treat, and release a wild mare with native PZP.
How long should we wait for the perfect solution? I hope our legislators and the BLM conclude that further delay in not using the best available tool we have—native PZP—makes no horse sense.
Source: OpEd Casper Star Tribune by Patricia M. Fazio, PhD
Patricia M. Fazio, Ph.D., is an environmental editor, historian, and scientist, with a special interest in the federal wild horse issue—leading to her dissertation on the Pryor Mountain Wild Horse Range, completed in 1995.
A young stallion named Gus just might be the key to saving the wild horses that roam the beaches of Corolla. The genetically-diverse wild stallion from Cedar Island, some 250 miles away, was released into the Corolla herd on Thursday.
“He’s the offspring of some Shackelford horses who are the same breed as ours – Colonial Spanish Mustangs. They have far more maternal lines than we do. We are down to one maternal line. Our gene pool is very shallow. We are having birth defects, so Gus is historic,” explained Corolla Wild Horse Fund Executive Director Karen McCalpin.
The process to get Gus into the herd has taken years and required approval from the U.S. Fish and Wildlife Service.
Earlier this year, McCalpin pulled DNA samples by dart gun from two wild stallions living on Cedar Island.
It was then analyzed by Dr. Gus Cothran of Texas A&M University who was able to confirm that the horses were Colonial Spanish Mustangs.
The Corolla Wild Horse Fund decided to name the stallion Gus in Dr. Cothran’s honor.
After Gus tested negative for Equine Infectious Anemia, staff from the CWHF made the trip to Cedar Island to transport Gus to the north beach in Corolla.
The herd on Cedar Island has been owned and cared for by Woody and Nena Hancock.
“Gus is the first step in turning that headed for extinction situation around. Without the introduction of new genes into the Corolla herd – they would cease to exist. We are already at a genetic bottleneck where we are having consistent birth defects in foals,” McCalpin told NewsChannel 3′s Todd Corillo on Monday.
“Obviously we are hoping Gus finds some girlfriends and that offspring that he would produce would be the first genetically-diverse offspring here in centuries. We hope if not next year, the year after we’re going to see a foal that we know is the beginning of turning around the path to extinction for these horses,” she continued.
As she watched Gus idly graze in his new Corolla home on an abnormally warm late-November day, McCalpin couldn’t help but be excited.
“Seeing him is probably bigger than winning the lottery for me. People talk about a bucket list and that was certainly on my bucket list. It’s just amazing to me that we were able to do this.”
McCalpin hopes to be able to return to Cedar Island in the spring to DNA test mares that could be released in Corolla as well.
Source: WTKR by Todd Corillo
The mission of The Corolla Wild Horse Fund is to protect, conserve, and responsibly manage the herd of wild Colonial Spanish Mustangs roaming freely on the northernmost North Carolina’s Currituck Outer Banks. The organization employs a darted immunocontraception program using the FDA approved substance PZP (porcine zona pelucida). It is conducted under the auspices of the Humane Society of the United States and the Science and Conservation Center in Billings, Montana.
If you would like to help the efforts to return the Corolla herd to genetic health, please donate. You can go to their website at www.corollawildhorses.org or by mail: CWHF P.O. Box 361 Corolla, NC 27927.
Largely unchecked by natural predators, many wild horse populations grow at rates of 18–25 percent per year. This unregulated growth can overtax vegetation and affect herd health as well as native wildlife populations. The Wild Free-Roaming Horses and Burros Act of 1971 requires the U.S. Bureau of Land Management (BLM) and USDA Forest Service to manage these free-roaming herds for a “thriving natural ecological balance.”
To ensure the sustainability and health of both horse herds and the public lands they roam, and to reduce the number of animals requiring either adoption or long-term care in holding areas, managers began to explore fertility control as an alternative management technique.
From 1978 into the 1980s, the BLM worked through a series of research contracts focusing primarily on development of a chemosterilant for wild stallions. In the early 1990s, research turned to silicone implants in mares in an effort to achieve fertility control. Although both routes produced fertility control, they had too many drawbacks and were eventually abandoned.
In light of these problems and the continuing need for some form of contraception, in 1991 researchers identified the desired characteristics for an ideal wild horse fertility control agent.
Specifically, the agent should:
How PZP works
In order for sperm to attach to the ovum and fertilize the egg, there must be complementary proteins on both the surface of the sperm and the zona pellucida (ZP) of the ovum. PZP acts as a foreign protein against which the treated mare produces antibodies (thus, the PZP fertility control agent is actually a vaccine). These antibodies attach to the mare’s zonae sperm receptors on the ovum and block fertilization. Domestic pig ovaries (obtained from slaughterhouses) are minced and the PZP is obtained from screening filtration. An adjuvant is mixed with the PZP to enhance its effectiveness when it is injected into mares intramuscularly. Once injected, it causes an immune response, making the mare infertile. Over time, the antibody titers fall and fertility returns. With the liquid vaccine, a booster injection can be given at 10 months to raise the titers back to the infertile range. This can be done each year for at least 4 years, after which time the effects may be more likely to become permanent. For this reason, current individual-level field trials involve only 1–4 years of treatment.
This list of needs would drive much of the U.S. research on wild horse contraception during the 1990s, including research funded by both the BLM and the U.S. Geological Survey (USGS). To meet the stated criteria, a National Park Service research team on Assateague Island National Seashore turned to an immunocontraceptive agent, porcine zona pellucida (PZP), which had been reported to block fertilization in dogs, rabbits, and primates. Experimental PZP application on the wild horses of Assateague Island commenced in 1988, resulting in promising reductions in the pregnancy rates of mares: by 1994, population growth began to stabilize solely through the use of PZP immunocontraception.
The Outlook for PZP
The PZP agent appears to meet most of the safety concerns of the BLM. The fact that PZP is a glycoprotein suggests that it should be digested before it can enter the food chain. Its effects passively wear off with time if annual injections are terminated; normal reproduction can be resumed following at least 4 years of use, and perhaps more. It does no harm if injected into mares that are already pregnant—they carry foals to term. Initial research suggests that PZP does not affect ovarian function or hormonal health. Life span seems to increase with improved health of treated mares, apparently due to the absence of stresses from pregnancy and lactation. Treated mares can live 5–10 years longer than untreated mares that continue to get pregnant and produce young. An initial study suggested that harem behaviors are not influenced, and more in-depth investigations are currently underway. There appear to be no generational effects; offspring of treated mares are able to reproduce normally. Finally, at least some forms of PZP may be 90% effective in blocking fertility in mares (see Wild Horse Resources, Fertility Control in Mares).
PZP has been successfully applied to control fertility in several small populations of wild horses on eastern barrier islands since the early 1990s. Population-level field trials of an injectable, time-release, pellet form of PZP that will allow almost 2 years of fertility control with a single treatment are currently underway in many western herds. The Assateague team also developed noninvasive methods to assess the pregnancy rates of, and detect ovulation in, free-ranging treated and nontreated, individually recognizable mares by analyzing reproductive steroid metabolites in their feces and urine.
PZP Field TrialsThe USGS, BLM, and USDA Animal and Plant Health Inspection Service (APHIS) have essentially completed individual-level field trials of PZP in free-roaming wild horses at three locations: Pryor Mountain Wild Horse Range, Montana and Wyoming; McCullough Peaks Herd Management Area, Wyoming; and Little Book Cliffs Wild Horse Range, Colorado. Application of PZP began in 2001 at Pryor Mountain, in 2002 at Little Book Cliffs, and in 2004 at McCullough Peaks. Results of this work in terms of horse behavior are reported in Ransom et al. (2010), and efficacy results are detailed in Ransom et al. (2011). In addition, in 2011 the USGS, BLM, and the Animal and Plant Health Inspection Service (APHIS; Department of Agriculture) began studies on the safety and efficacy of SpayVac®, a form of PZP made using a proprietary technology developed by Immunovaccine Inc. (Halifax, Nova Scotia, Canada).
Source: USGS, Fort Collins Science Center
HORSES FOR LIFE