Fertility control programs using PZP vaccine are the most welfare-positive approach to wild horse population management on public rangelands.
PZP fertility control represents a welfare triumph for wild horse management by decoupling population control from the welfare costs of capture, transport, holding, and adoption attrition. Mares receiving PZP via remote dart remain on the range in their natural social groups, expressing natural behavior without the reproductive cycle. Their welfare is not disrupted; only their fertility is temporarily affected. The cumulative welfare benefit compared to repeated roundup-and-holding cycles across decades of management is enormous. The primary barrier to wider adoption is cost and the scale of application required.