Pinworm in Horses: Symptoms and How to Test

Pinworms (Oxyuris equi) are a common intestinal parasite in horses, especially young and stable-kept animals. While they are usually not life-threatening, they can cause discomfort and irritation. Understanding how to detect and manage pinworm infections is key to keeping your horses healthy.

What Are Pinworms?

Pinworms are small, white worms that live in the horse’s large intestine. Female pinworms travel to the horse’s anus to lay eggs, which causes intense itching around the tail and perineal (anus) area.

Signs of pinworm infection include:

• Tail rubbing or hair loss around the tailhead
• Restlessness, especially at night
• Occasionally, mild irritation or swelling around the anus

Unlike strongyles, pinworms rarely cause serious health problems, but they can be very irritating for your horse.

How to Test for Pinworms

Pinworms are best detected using a tape test rather than a faecal sample, as the eggs are laid around the anus rather than passed in manure. Here’s a step-by-step guide:

1. Gather Your Materials

• Clear sticky tape (Scotch tape works well)
• Small glass or plastic bag for the sample
• Gloves (optional, for hygiene)
• A microscope slide (can be collected in-store)

2. Collect the Sample

• Early morning is best, before your horse has passed manure or moved around.
• Press a strip of clear tape firmly onto the horse’s perineal area.
• Gently lift the tape - this will pick up any pinworm eggs present.
• Place the tape sticky-side down on a microscope slide or inside a sealed bag for submission.

3. Submit for Testing

• Drop the sample off in-store for analysis
• Multiple samples over consecutive days may improve detection accuracy, as egg laying can be intermittent.

Treatment and Prevention

If pinworm eggs are detected, your veterinarian may recommend a Benzimidazole (BZ) or pyrantel-based wormer, as these are effective against Oxyuris equi.

To reduce reinfection:

• Maintain good paddock hygiene, removing manure regularly
• Avoid overcrowding and rotate pastures when possible
• Monitor horses showing tail rubbing and test periodically

Key Takeaway

Pinworms are more of an irritation than a serious threat, but early detection and proper hygiene are essential. Collecting a perineal tape sample is simple, non-invasive, and allows for accurate diagnosis, so you can treat your horse promptly and prevent ongoing discomfort.