Durvet Ivermectin Paste 1.87% wormer for horses combats large strongyles, bots, small bloodworms, threadworms, roundworms, large mouth stomach worms, lungworms, and pinworms. The apple flavor makes this treatment more palatable and easier to give. Each syringe contains enough to treat a horse that weighs up to 1,250 lbs, and is safe for use in breeding stallions, pregnant mares, and foals when used according to the instructions or by the direction of your veterinarian.