Foals are more susceptible to equine parasites compared to adult horses – so when is treating with Ivermectin for foals appropriate?
Worming mares & foals
Exposure to parasites begins at such an early age. Worms can find their way to the foal through their mother’s milk, or they can ingest the eggs of the parasites from manure.
Mares should be wormed 4-6 weeks before foaling or within 24 hours after foaling.
Dewormers should be carefully used around foals; some agents may not be recommended in foals at a specific age. For instance, moxidectin is not recommended for use in foals less than six months old.
You can use ivermectin for foals from the age of 8 weeks.
For foals less than 12 months, deworming can already be a good practice. Using an ivermectin dewormer is essential in controlling roundworms (also known as ascarids).
Roundworm: The large roundworm or ascarid primarily affects horses less than two years of age. Ascarids are the most significant parasite in young horses because they are such large worms and can quickly develop into life threatening numbers. Ascarids have the potential to cause liver damage, which is repairable, and lung damage, which is permanent.
Tapeworm: Tapeworm infestation is rare in foals that are less than seven months old.
Strongyles: Large strongyles (sometimes called bloodworms) are found in the large intestines either attached to the walls or in the intestinal contents. All horses can be affected by strongyles but young horses are most vulnerable. Signs of strongyle infection are loss of appetite, weight loss, fever, depression, weakness, anaemia, diarrhoea and death.
Creating a foal worming program
In young horses during the first year of life foals should receive a minimum of four deworming treatments.
First deworming should be carried out at about 2-3 months of age, and a benzimidazole drug is recommended to ensure efficacy against large roundworms.
Second deworming is recommended just before weaning (approximately six months of age).
At weaning fecal egg counts are recommended to determine whether worm burdens are primarily strongyles or large roundworms, to facilitate the right choice of drug class.
Third and fourth treatments should be considered at about 9 and 12 months of age, respectively, and treatment should primarily be targeting strongyles.
Tapeworm treatment should be included on one of these latter treatment occasions. Recently weaned foals should be turned out onto the “cleanest” pastures with the lowest parasite burdens.
Pasture Management for Worms
Keeping the horse’s environment clean is a vital step in preventing and controlling parasite infestation. Complete eradication of parasites from the surroundings is close to impossible, which is why it is better to keep the parasites well controlled to avoid problems. This way, you are helping adult horses as well as their newborn and incoming foals avoid equine parasite infestation as much as possible.