Porcine zona pellucida (PZP) fertility control programs for feral horses offer a humane alternative to roundups. Expanding and refining these programs is key to sustainable, welfare-compatible horse management.
PZP fertility management represents the most welfare-aligned approach to feral horse population management because it allows horses to remain in their established home ranges with intact social groups. Wild horses live in complex family bands with strong social bonds; roundup breaks these bonds, causes transport stress, and confines animals to holding facilities for potentially years. PZP avoids all of these welfare costs while achieving the population management goal. The main welfare improvement needed is expansion of PZP delivery capacity to reach more horses annually; current programs are underfunded relative to the scale of management needed. Each mare successfully contracepted prevents multiple future births requiring management, making PZP cost-effective over time.