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Horse Deworming Schedule & Medicines

Horse Deworming Schedule & Medicines

Parasites pose a risk to all animals, and the horse is no exception. It is essential to deworm your horse in order to maintain their health. Our Hohenwald vets will discuss deworming horses, when to do it, and methods to minimize worm infection in your horses.

What Types of Worms Are There and What Problems Do They Cause?

In this article, we will discuss four types of worms that can cause problems in horses. The list is not complete, we are just a selection of some of the most common worms that affect horses.

Small Redworms (Cyathostomes)

This worm lives in the horse's stomach. Horse parasites are a common problem. The eggs are embedded in the intestines. The eggs tend to go dormant during the winter and hatch in the spring, resulting in a sudden and large amount of parasites flooding the horse's body. The sudden influx of parasites that consume the horse's nutrients can be deadly. They can cause the following symptoms:

  • Weight loss
  • Diarrhea
  • Colic

Large Redworms (Strongyles)

There are several different varieties of strongyles worms included in the term large redworms. They are considered to be one of the most dangerous worms to infect horses. After being ingested, the eggs of the worms reach the horses bloodstream. While they are in the blood vessel, they tend to block blood flow, which damages the tissue that is supplied by the blood vessel.

Symptoms of these worms include:

  • Colic
  • Rapid weight loss
  • Diarrhea.

Bots (Gastrophilus)

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

Roundworms (Ascarids)

Roundworm is especially dangerous for horses with a weak immune system, like foals and older horses. The parasite is consumed through contaminated food (grass that has come in contact with the fecal matter of an infected horse) or through contaminated food. It migrates from the intestine to either the lungs or the liver. Before returning to the intestines to lay their eggs and start the cycle again, these worms can cause severe damage to the organs.

How Often Should I Deworm My Horse?

How often you need to deworm your horse will depend on a lot of different things. The amount of eggs your horse is excreting in its manure is a key factor. For most horses, twice yearly, often done in the spring and fall, is recommended. If your horse is highly infected, you should increase the frequency of doses. We recommend consulting with your veterinarian to determine how often your horse needs to be dewormed, based on a fecal examination.

Deworming for foals is often done every 2 months for the first year, with regular fecal exams.

What Medicine Should I Use to Deworm My Horse?

The type of medicine used will depend on the results of their fecal exam. Depending on the types 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 Equine Vaccinations & Prevention page.

Methods to Avoid Parasites

Besides deworming and regular vet visits with fecal exams, some methods to help control parasites in horses include:

  • 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 Can I Tell if My Parasite Control Program is Working?

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.

Do you need help with your horse's deworming? Contact Hohenwald Animal Hospital today and book an appointment to see our vets. 

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