Porcine zona pellucida (PZP) immunocontraception of wild horses (Equus caballus) in Nevada: a 10 year study.

J. W. Turner, Irwin Liu, D. R. Flanagan, K. S. Bynum, A. T. Rutberg

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Porcine zona pellucida (PZP) immunocontraception was investigated for possible use in free-roaming wild horses in the western USA. A protocol of two injections (3-4 weeks apart) of vaccine lasting 1 year was first used and a single-injection controlled-release vaccine of 1 year duration was developed and tested in the field. Studies of a presumptive vaccine of 2 year duration were initiated. The parameters of anti-PZP antibody titre response, pregnancy testing and offspring production were used, and PZP vaccine was found to provide up to 94% infertility in free-roaming wild mares. In addition, a single-injection PZP vaccine of 1 year duration and containing a controlled-release component of PZP in a polymer matrix can provide infertility equivalent to the two-injection PZP vaccine. All the PZP vaccine preparations tested were associated with a return to normal fertility within 1 year. During the course of these studies, attention was given to practical aspects of management application of PZP contraception. Preparation of the controlled-release portion of the vaccine in pellets, which fit into the needle of a dart or syringe, has simplified vaccine handling and permitted long-term storage of the controlled-release component. Vaccine delivery is now performed using a jabstick on captured mares restrained in a field stock chute during routine horse gathers. Provision of a vaccine-training programme has maximized personnel safety during vaccine preparation and use.

Original languageEnglish (US)
Pages (from-to)177-186
Number of pages10
JournalReproduction (Cambridge, England) Supplement
StatePublished - Jan 1 2002
Externally publishedYes


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