Equine reproductive immunology Ph.D speaks out in 2010 against using PZP on wild horses

Native Wild Horses (Photo © Cynthia Smalley, all rights reserved)

Native Wild Horses (Photo © Cynthia Smalley, all rights reserved)

November 27, 2010 

Jared Bybee, Wild Horse and Burro Specialist 

Department of the Interior 

Bureau of Land Management 

Billings Field Office 

5001 Southgate Drive 

Billings, Montana 59101-4669 

VIA FAX: 406-896-5281 

RE: Pryor Mountain Wild Horse Range Fertility Control Preliminary Environmental 
Assessment Tiered to the Pryor Mountain Wild Horse Range Environmental Assessment 
and Herd Management Area Plan May 2009 EA DOI-BLM-MT-0010-2011-0004-EA 

Dear Jared Bybee: 


I appreciate the opportunity to submit comments on the Pryor Mountain Wild Horse Range 
Fertility Control Preliminary Environmental Assessment Tiered to the Pryor Mountain Wild 
Horse Range Environmental Assessment and Herd Management Area Plan May 2009 EA DOI-
BLM-MT-0010-2011-0004-EA. My background is in equine reproductive immunology and 
wildlife conservation. I applaud the Billings Field Office of the Bureau of Land Management 
(BLM) for a thoughtful approach to this issue. Cover letter 4700 (010.JB) dated November 1. 
2010 and signed by James M. Sparks, Field Manager states that the BLM would consider 
comments and revision to the EA or unsigned FONSI as appropriate. I urge a “no action 
alternative” as outlined on page 7 and 8 of the EA. This request is based on two pieces of new 
scientific evidence about effects of current immuno-contraception use. 

Porcine Zona Pellucida (PZP) Contraception 

The proposed action as stated on page 7 of this EA would exempt “mares ages 5-10 unless they 
have produced foals, or are part of a large bloodline.” This is reminiscent of the approach taken 
with the Assateague Island wild horse population. It is a compromise approach to this issue, in 
comparison to placing all mares on PZP. However a recent study shows that mitochondrial DNA 
diversity is low in the Assateague Island horse herd (Eggert et al. 2010). Since mitochondrial 
DNA is inherited from the mother (mare), this is evidence that female inherited genetics on 
Assateague Island wild horses is under represented. It is imperative that this be assessed before 
rolling out a similar management plan for the Pryor Mountain wild horses. 

There is a recent Princeton University study on PZP effects. Consecutive PZP applications, 
analogous to the proposed action plan in this EA, showed that mares gave birth later in the 
season, and were cycling into the fall months (Nunez et al. 2010). In a state like Montana where 

freezing temperatures are found in the fall, this can have serious and long term effects on foal 

I must include a statement on long term consecutive use of PZP. Any form of PZP contraception 
is not completely reversible in mares depending on the length of use of PZP. Contraception can 
only be reversed when the antibody titer decreases to 50-60% of the positive reference sera (Liu 
et al. 2005). Mares treated for 7 consecutive years do not return to viable fertility (Kirkpatrick 
and Turner 2002; Kirkpatrick et al. 2009). The issue of reversible contraception is very important 
to be able to maintain wild equines in the United States. Long term treatment with PZP has 
inherent negative potential for this herd. 

I am requesting a new look at the proposed fertility control action for the Pryor Mountain wild 


Christine DeCarlo, Ph.D. 

Lori S. Eggert, David M. Powell, et al. (2010). "Pedigrees and the Study of the Wild Horse 
Population of Assateague Island National Seashore." Journal of Wildlife Management 
74(5): 963-973. 

J. F. Kirkpatrick, A. Rowan, et al. (2009). "The practical side of immunocontraception: zona 
proteins and wildlife." J Reprod Immunol 83(1-2): 151-7. 

J. F. Kirkpatrick and A. Turner (2002). "Reversibility of action and safety during pregnancy of 
immunization against porcine zona pellucida in wild mares (Equus caballus)." Reprod 
Suppl 60: 197-202. 

I. K. Liu, J. W. Turner, Jr., et al. (2005). "Persistence of anti-zonae pellucidae antibodies 
following a single inoculation of porcine zonae pellucidae in the domestic equine." 
Reproduction 129(2): 181-90. 

Cassandra M. V. Nunez, James S. Adelman, et al. (2010). "Immunoctraception in Wild Horses 
(Equus caballus) Extends Reproductive Cycling Beyond the Normal Breeding Season." 
PLos ONE 5(10): 1-10.

(Posted for educational purposes)

Stop the Roundups Rally in Sacramento July 10th at 2 pm outside the Federal Courthouse

Come to the rally to show that you care about the wild horses and burros in America.

Terri Farley speaks at the Rally to Stop the Roundups (Photo © Anne Novak.)

The Sacramento Stop the Roundups Rally and Press Conference is at 2 p.m. July 10th on the sidewalk outside the Federal Courthouse across from the Amtrak station. ( 501 ” I ” Street at the 5th Street intersection in Sacramento, CA 95814)

Here is a list of speakers:

Carla Bowers, National Wild Horse Advocate

Tina Brodrick, Owner of Sonny Boys Tours

Craig Downer, Wildlife Biologist and acclaimed Wild Horse and Burro Expert

Terri Farley, Award winning writer and beloved author of The Phantom Stallion series

Cat Kindsfather, Award winning wild horse photographer

Marilyn Kroplick, MD, Board President for In Defense of Animals

Simone Netherlands, President of Respect for Horses

Anne Novak, Executive Director of Protect Mustangs

Jetara Séhart, Executive Director of Native Wild Horse Protection & Marin Mustangs

Robin Warren  (Wild Mustang Robin), Director of The Youth Campaign for Protect Mustangs

Bring homemade signs and your friends. It will be hot so bring a rain umbrella for shade and plenty of water. Protect Mustangs encourages members of the public to carpool or take Amtrak to save on fuel and reduce pollution. Oil and gas extraction–on public land–is one of the main reasons wild horses are being wiped off their home on the range.  Be part of the solution and take the train if you can.

The voiceless wild horses and burros need your help after the rally too. Give oral or written comment against helicopter roundups and attend the 6:30 pm BLM Wild Horse & Burro Helicopter/Vehicle Use Public Hearing for roundups and management. The meeting runs from 6:30-8:30 PM at the Woodlake Hotel (formerly the Radisson near Arden Fair Mall) 500 Leisure Lane in Sacramento.

“Like” and check for updates on our Facebook page: http://www.facebook.com/ProtectMustangs

Join the dynamic conversation on Facebook about helicopter roundups: http://www.facebook.com/photo.php?fbid=387209591338066&set=a.240625045996522.58710.233633560029004&type=1&theater

Driving directions from the rally to the meeting:

Driving directions to 500 Leisure Ln, Sacramento, CA 95815
501 I St
Sacramento, CA 95814
1. Head north on 5th St toward H St
194 ft
2. 5th St turns right and becomes H St
0.8 mi
3. Turn left onto CA-160 N/16th St

Continue to follow CA-160 N
2.3 mi
4. Take exit 47A for Leisure Ln towardCanterbury Rd
0.1 mi
5. Keep left at the fork, follow signs forLeisure
79 ft
6. Turn left onto Leisure Ln

Destination will be on the right
354 ft
500 Leisure Ln
Sacramento, CA 95815

Special thanks to Jetara Séhart, Executive Director of Native Wild Horse Protection & Marin Mustangs for her help to put together this event.

If you have any questions or would like to speak at the rally feel free to send us an email at Contact@ProtectMustangs.org