Equine Deworming Plan

Equine Deworming Plan

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The recent increase in parasite resistance to commonly used deworming products has left the equine community concerned and in search of ways to slow down, if not reverse, the alarming trend. As parasites can pose a very serious threat to a horse’s health, including fatal situations, it is apparent that the commonly accepted approach to parasite control should be reconsidered. For example, the so called dewormer “rotation” is no longer an acceptable practice.

Strongyles, roundworms, bots, pinworms, and tapeworms are some of the parasites that veterinarians and horse owners deal with. Some of these can be identified easily, others not so much. That is why every treatment should start with analyzing fecal samples. The test is relatively inexpensive, and can provide a solid basis for choosing the right product that will ensure an effective deworming treatment. Every horse from the herd should be tested, but if the group is very large, then a proportionate test group may be used to gather samples from. The fecal test should be done once a year or at least every other year.

Statistically, horses can be categorized as follows:

If you test the whole herd individually you may find that not all horses carry the same amount and/or type of parasites. Some horses will carry a lot of worms and others much less. This is due to individual immunity, genetics, exposure level, and a variety of other factors. It may be a good idea to group horses based on the parasite type of infestation they have. This may help prevent further transfer of eggs and larvae between individuals.

There is no longer any fixed time chart or an ideal schedule for equine deworming. Instead, a proper deworming program will be based on the level of infestation and on the climate in your area. It is strongly recommended to perform a treatment after the first killing frost in the late fall to control bots and another round in the spring with a praziquantel- containing dewormer, which will provide a solid tapeworm control program. Note that this is the minimal treatment for the so-called light shedders.

Always consult your veterinarian before treatment. Fecal testing can help determine the right product and the most effective way to treat your horses. The currently preferred drugs are pyrantel (not effective for tapeworm or bot treatment), ivermectin, moxidectin, and praziquantel (effective against tapeworm).

*Craig R. Reinemeyer, DVM, PhD, The Horse.com, “What is your Horse’s Fecal Egg Count Telling You?”, April 17, 2017

Resistance

Resistance

Resistance is the ability of worms in a population to survive treatment by a particular deworming chemical. Resistance grows when parasites survive treatment, and then pass the ability to survive on to their offspring.

Factors that influence resistance growth¹:

• Under dosing.
• Deworming frequency.
• Using dewormers that do not kill resistant parasites.

Resistance can be reduced by:

• Use the proper dose and ensure the horse ingests the full dose.
• Deworm only when needed.
• Use dewormers that are effective. Studies have shown certain deworming classes, e.g. benzimidazoles have a high rate of resistance².

80% of horses in a recent study³ whose weights were set visually were underestimated. Optimally, weigh your horse. This can be done when trailering, weigh your vehicle with your horse and without (scales can be found at feed mills, truck stops etc). If a scale is unavailable, weight tapes use a combination of a horse’s girth and height to estimate weight. Use care, weight tapes can be inaccurate for foals, miniatures and heavily muscled and high withered horses.

Know how many pounds the dewormer treats. This varies by brand, by as much as 20%. Round up to the nearest measurement and securely lock the syringe mechanism in place for that dosage.

Be sure once administered the horse ingests the full dose. This can be aided by raising the horses head and stroking under their jaw. Apple flavored dewormers can increase the ease of dosing, this can help reduce spit outs and other activities that prevent a full dose from being ingested.

How to Administer

How to Administer