There are many types of internal parasites in a horse and there are also several products on the market with various active ingredients.  Choosing an effective program for your horse can be very confusing.

The best starting point is talking with your veterinarian.  He or she can help you develop a program based on your horse’s age, health status, location, season, life style (travel, pasture mates, type of pasture etc.).  An inadequate program puts your horse at risk for increased exposure to parasite eggs and larvae.  Your veterinarian may order a fecal test to determine the type of parasites and level of infestation.

Common parasites in a horse: Some of the common parasites in horses include roundworms, pinworms, tapeworms, large strongyles, (bloodworms), small strongyles and bots.

Symptoms of parasitic infestation: Depending on the type, parasites can cause stunted growth, anemia, diarrhea, colic, weight loss, damage to blood vessels, ulcerations, poor coat, tail rubbing, unthriftiness, etc.

Dewormers: A dewormer is given to eliminate the parasites and prevent their reoccurrence. Depending on the active ingredient a dewormer can be a broad spectrum one, covering a wide range of parasites, or it can target a specific type of parasites. You can choose a product based on your individual needs, and your vet may also advise you to combine them.

Dewormers are available as paste, gels, powders, granules and pellets. You can choose the form based on your horse’s acceptance, and the ease of administration.

Deworming Programs:

  1. Oral broad-spectrum deworming: Sometimes called purge dewormers, these target a wide range of parasites in various stages of life. The majority of the broad spectrum dewormers contain Ivermectin as an active ingredient.  Ivermectin is very effective against a wide range of parasites and is safe when used as directed.  There are products that may contain another active ingredient in addition to Ivermectin.  These cover parasites which are not controlled by Ivermectin alone.  Some products that would be considered “oral broad-spectrum” dewormers would include: Agri-Mectin Paste (Agri-Labs), Strongid Paste (Strongid), Zimecterin Gold (Zimecterin), and Ivermectin Paste (Durvet).

  2. Rotational Deworming:  This program combines two or more purge dewormers, each used at specific times throughout the year. Here, a broad-spectrum dewormer is combined with a specific product to target like tapeworms.  This program may also help prevent parasite resistance to the dewormer.  Its success is also based, in part, on your horse already being infested with parasitic worms.

  3. Continuous Deworming involves daily deworming.  Here a dewormer such as Continuex (Farnam) or Strongid C-2X is given as daily feed additive to continually protect your horse against internal parasites.  Daily dewormers help prevent parasite re-infestation. It is advisable to combine daily deworming with a twice-yearly broad-spectrum purge dewormer.  The key to the success of this program is making sure your horse is getting the daily dose.  Missed doses decrease the product’s efficacy.

With the help of your veterinarian you can choose a program which will be effective for your horse, in your area, and for your management conditions.  Regardless of the recommended treatment, it is likely that your veterinarian will suggest using an equine probiotic supplement.

In addition to deworming your horse, good management practices like removing manure from the pasture regularly, avoiding overcrowding, and having elevated feeders for grain and hay are vital to keeping your horse parasite free.

Every time you use a dewormer, it is advisable to give your horse a good probiotic supplement.  Probiotics help maintain the levels of beneficial bacteria in the gut which is vital for gut and general health.  Try Probios Horse Treats-Digestion Support, or Probios Equine One Oral Gel.