The researchers examined the effects of PZP on the body condition of adult females, the timing of the breeding season and the survival of their offspring, finding that
- The body condition of mares without foals improved faster than mares with foals
- The foaling seasons of the treated herds were later in the year and more spread out
- Deaths of foals born to treated mares through their second year of life were very rare and no more frequent than those of foals born to untreated mares
The research was carried out at Cedar Mountain and Sand Wash Basin.
Although the timing of breeding changed, the writers found no evidence that the changes were harmful to the treated mares or their foals.
Not addressed in the report:
- Risk of sterility
- Loss of genetic diversity
- Skewing of sex ratios
- Selection for weak immune systems
The authors claimed no conflicts of interest but one of them is with the Science and Conservation Center, manufacturer of the pesticide and home of the Billings School of PZP Darting and Public Deception.
Funding was provided in part by the Humane Society of the United States, holder of the EPA registration.
Western Horse Watchers Association 