The frequency of worming a horse varies by factors like age, environment, and individual parasite load, but the modern recommended approach is more customized than fixed intervals. For most healthy adult horses, worming once or twice per year is generally sufficient, ideally timed with seasons when parasite larvae are most active (e.g., spring and autumn). However, horses with higher parasite burdens, younger horses (foals), or those with compromised health may need more frequent worming or testing. A strategic and targeted worming approach based on regular fecal egg counts (FECs) is widely advised. This involves monitoring parasite levels in horse manure and only treating those with significant worm burdens, which helps avoid unnecessary worming and reduces drug resistance. Testing intervals often recommended are every 3 to 6 months depending on the setting. For foals, more frequent deworming is needed, with at least four treatments in the first year, starting as early as four weeks old for threadworms. In summary:
- Adult horses: 1–2 times per year worming if fecal counts are low.
- Horses with high egg counts: worm more frequently, based on veterinary advice.
- Foals and immunocompromised horses: more frequent treatments.
- Use fecal egg counts to guide worming frequency (every 3-6 months).
- Worming timing often targets spring and autumn for optimal parasite control.
This strategic approach both protects the horse's health and reduces the risk of anthelmintic resistance.
