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Symptoms of worm infections in horses

The symptoms of a parasite infection can vary depending on the type of worm involved and the number of worms infecting the horse. Many parasite infections will have no symptoms when the parasite burden is low, but a high number of worms can cause symptoms and seriously affect the horse’s health.

Common signs of parasite or worm infection include:

Weight loss


Diarrhea or constipation

Rough hair coat

Poor growth in foals

Respiratory problems

(nasal discharge, cough)

How do we diagnose a parasite or worm infection?

The diagnosis of a parasite infection can vary depending on the species involved, and some of them can be challenging to identify. A veterinary examination is recommended if a horse has symptoms of a parasite infection. The veterinarian might prescribe additional testing to determine whether the patient is infected with worms.

The most common test used to diagnose a parasite infection is the fecal egg count. This simple test involves counting the number of parasite eggs in a small amount of feces. This is the ideal test to diagnose the most common equine parasites, like small and large strongyles and roundworms.

A targeted deworming approach involves determining the fecal egg count of each individual to devise a treatment plan tailored for each horse.