There is no single parasite control program ideal for all horses. The selected program should include a risk evaluation for parasites through mare fecal analysis for parasites, climate, and pasture management techniques. Mares should be routinely dewormed throughout pregnancy with a rotation of dewormer classes. Immediately after birth (within 24 to 48 hours), mares should again be dewormed to reduce both ova in feces that may expose foal and to reduce migrating Strongyloides westeri that may be in mare’s milk.
Environmental control of parasite exposure can be very effective in reducing parasite exposure. Manure should be picked and removed from pasture and composted away from graving horses. Pasture should be mowed and/or harrowed routinely to break up any remaining manure piles. Foals and yearlings should be pastured away from older horses to prevent exposure to ascarids.
Routinely, foal deworming should begin at two months of age. Foals should be dewormed at the same time as their dam and other horses in their pasture group. Foals can be treated with the same rotation of dewormer classes as the adult horses (avermectin/milbemycins, benzimidizoles, and pyrimidines). Specific wormers may be used based on fecal egg counts.