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Horse Deworming Schedule & Medicines

Horse Deworming Schedule & Medicines

Just as they are a concern with the pets and members of your family, parasites are also able to infect your horse leaving them unwell. In this post, our New Ulm vets share the types of worms that might infect your horse when to have your horse dewormed and how you can protect them.

The Different Types of Worms / Parasites That Affect Horses

Here, our equine vets in New Ulm talk about the main types of worms/parasites that may infect your horse and how they can be treated and prevented.

Cyathostomes or Small Redworms 

This worm is one of the most common parasites affecting horses. This worm lives in the horses' intestines and embeds its eggs in the intestinal wall. The eggs tend to go dormant during the winter and hatch when it is spring resulting in a sudden and large amount of parasites flooding the horse's body. This sudden increase in the number of parasites can be detrimental to the nutrient retention of the horse. The symptoms they can cause are:

  • Weight loss
  • Diarrhea
  • Colic

Strongyles or Large Redworms 

The term 'large redworms' incorporates several different varieties of strongyles worms. They are considered some of the most dangerous worms to infect horses. The eggs of the worms are ingested and then they make their way to the horse's bloodstream. These worms obstruct the flow of blood through the blood vessels which can cause serious damage to the tissues.

Symptoms of these worms include:

  • Colic
  • Rapid weight loss
  • Diarrhea.

Gastrophilus or Bots (Bot Fly)

Bots are the worm form of the bot fly. When the bot flies lay their eggs on the coats of the horse, the horse tends to ingest them when they lick themselves to groom. Once in the horse, they hatch and migrate to the stomach.

Symptoms include:

  • Inflammation in the mouth
  • Inflammation in the throat
  • Ulceration in the stomach

Ascarids or Roundworms 

Roundworms are particularly dangerous for horses with a weak immune system such as foals and elderly horses. The parasite is consumed through contaminated food (grass that has come in contact with the fecal matter of an infected horse). The parasite migrates from the intestine to either the lungs or the liver. These worms can cause severe damage to these organs before returning to the intestines to lay their eggs and start the cycle again.

How frequently do horses need deworming?

How often you need to deworm your horse will depend on certain factors. A key factor is how many eggs your horse is excreting in their manure. For most horses, twice yearly, often done in the spring and fall, is recommended. If your horse is highly infected then the frequency of doses should increase. We recommend consulting your veterinarian about how often your horse needs to be dewormed based on a fecal exam.

During the first year of a foal's life, your vet will perform deworming every 2 months along with routine fecal exams.

What medication is used in deworming horses?

The type of medicine used will depend on the results of their fecal exam. Depending on the type of worms present different dewormers will work better than others. Some common medicines are ivermectin and moxidectin. For the types of deworming medication we offer, please see our Large Animal Care page.

What are some of the ways that you can prevent parasites?

Besides deworming and regular vet visits with fecal exams, some of the other ways that you can help protect your horse from parasites are:

  • If you are getting a new horse they should be quarantined while they undergo a precautionary deworming and subsequent fecal exam.
  • Remove fecal matter from pasture regularly to reduce reinfection.
  • Rotate pastures to avoid contamination.
  • Do not overcrowd the pasture.

How will you know that the parasite medication is working for your horse?

The best way to tell if you're controlling the parasite is to have your vet do tests such as fecal exams, to gauge the health of your horses.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Is your horse in need of routine parasite prevention? Contact New Ulm Regional Veterinary Center today and request an appointment with our New Ulm vets. 

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