Horse Deworming Schedule & Medicines

Parasites are a risk all animals face, including horses. Routinely deworming your horse is vital to their health, as is knowing when to do it. Here, our Union City vets discuss the schedule for deworming horses and how to go about it.

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

There are 4 most common types of worms that can cause issues in horses. This is not a complete list, but it is the 4 parasites most horse owners should know by name. Below are these common worms found in horses and the health issues they cause.

Small Redworms (Cyathostomes)

The most common of these 4 parasites. Small Redworms embed their eggs in the intestinal wall until they all hatch at once, causing a potentially deadly onslaught of parasites inside the horse. Symptoms include:

  • Weight loss
  • Diarrhea
  • Colic

Large Redworms (Strongyles)

These are considered some of the most dangerous worms to infect horses. The horse ingests the eggs of the Large Redworm, and the eggs get into the bloodstream, contaminating and damaging tissue. Symptoms 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)

These are particularly dangerous for horses with a weak immune system, like foals and senior horses. The parasite is consumed through contaminated food (grass with fecal matter on it) where it migrates from the intestine to either the lungs or the liver. They cause severe damage to these organs before laying their eggs and beginning the cycle again.

How Often Should I Deworm My Horse?

How often you need to deworm your horse depends on a few key factors:

  1. How many eggs your horse is excreting in their manure.
  2. How frequently your horse gets infected with worms.
  3. Your horses age (foals and senior horses have different immune system requirements than adult horses).

In general, it is recommended to deworm your horse twice yearly in the Spring and Fall. We recommend consulting your veterinarian about how often your horse needs to be dewormed based on a fecal exam.

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. The type of deworming agent needed depends on the type of parasite in the horse. Some common medicines are ivermectin and moxidectin. For more information, please see our Equine Services page.

Methods to Avoid Parasites

Some methods to help control parasites in your horse include:

  • If you are getting a new horse, they should be quarantined while they undergo a precautionary deworming and 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 only accurate way to know if your parasite control is effective is by taking the horse to the vet so they can perform fecal tests. This will gauge the animal's approximate health. If any changes to medication or the deworming process are needed, your vet will be able to make these recommendations.

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 Reelfoot Animal Hospital today and book an appointment to see our vets in Union City.