Foals should be dewormed for the first time at 30 days of age. The recommended dewormer is fenbendazole, which is the active ingredient in the dewormers Safe-Guard and Panacur. Foals should be dewormed every month until they are 18 months old.
We usually recommend using fenbendazole for the first four months. After that time, an ivermectin product may be used, but ONLY if you have been deworming your foal as regularly as we have recommended. If ivermectin is used and the foal has not been routinely dewormed, there may be a massive kill of large roundworms. These worms can obstruct the intestine, which can be and most often is, fatal for the foal.