Screwworm: What Every Horse Owner Should Know

If you’re anything like me, you probably spend a good portion of your day worrying about things that may never happen.

Is my horse limping?

Did he always have that bump?

Why is he staring at me like that?

And now, thanks to recent headlines, many horse owners are asking a new question:

What in the world is a screwworm?

The name alone sounds like something straight out of a horror movie. Unfortunately, it’s real.

Before you start wrapping your horse in bubble wrap and moving him into your living room, let’s talk about what screwworms are, why horse owners are paying attention, and what you can do to protect your horse.

First Things First: What Is a Screwworm?

Despite the name, a screwworm is not actually a worm.

It’s the larva (maggot) of a particular fly that lays its eggs in open wounds. When the eggs hatch, the larvae feed on living tissue.

Yes. Living tissue.

I know. I wish I didn’t know that either.

Unlike common maggots that typically feed on dead tissue, screwworm larvae burrow deeper into healthy flesh. That’s what makes them such a serious concern for livestock, wildlife, pets, and horses.

How Could This Affect My Horse?

The scary part is that the fly doesn’t need a huge injury.

A screwworm fly can be attracted to:

Small cuts and scrapes
Wire wounds
Surgical incisions
Hoof abscess drainage sites
Tick bites
Castration sites
Umbilical areas on newborn foals
Eyes, nostrils, and other natural openings

In other words, all those little horse injuries we often shrug off and say, “Eh, it’ll heal.”

Those are exactly the places that deserve a second look.

The Day I Realized Horses Are Professional Injury Creators

Have you ever turned your horse out looking perfectly normal and then brought him in six hours later with a mysterious cut on his shoulder?

No blood trail.

No witness.

No explanation.

Just a new injury.

Horses have a special talent for hurting themselves in ways that defy all known laws of physics.

That’s why regular wound checks are so important. Small wounds can become big problems if they’re ignored.

Signs Something Isn’t Right

A normal wound should slowly improve.

A wound with screwworm infestation tends to do the opposite.

Watch for:

Excessive drainage
A foul odor
Swelling
Increased pain
A wound that seems to be getting larger
Visible larvae
Unusual irritation or rubbing

If you ever see maggots in a wound, call your veterinarian immediately. Don’t wait to “see what happens.”

Trust me, that’s one surprise nobody wants.

Are Screwworms In Nevada?

At the time of writing, screwworms are not established in Nevada.

That’s the good news.

The better news is that horse owners already know how to do many of the things that help prevent problems:

Clean wounds promptly
Use fly control around the barn
Check horses daily
Monitor healing injuries
Call your veterinarian when something doesn’t look right

In other words, the same good horse management that protects against countless other problems helps protect against screwworms too.

The Bigger Lesson

Every now and then a new horse-health headline pops up and sends us all down an internet rabbit hole.

I’ve learned that the goal isn’t to panic.

The goal is to pay attention.

Horse ownership has taught me that most problems don’t become disasters overnight. Usually there are little clues along the way if we’re paying attention.

A horse who suddenly feels off.

A hoof that doesn’t look quite right.

A wound that isn’t healing normally.

The best thing we can do is notice those clues early and act on them.

Final Thoughts

Will your horse get screwworms?

Probably not.

Should you be aware of them?

Absolutely.

The next time you’re grooming your horse, running your hands over every inch of him, and wondering how he managed to acquire yet another mystery scrape, take an extra minute to inspect it.

Because when it comes to horse health, catching problems early is always easier than fixing them later.

And if your horse somehow manages to get a new cut while standing alone in a perfectly safe pasture?

Well, that’s a topic for another blog post.

Happy riding, and give your horse a scratch for me.

Disclaimer: I am not a veterinarian. The information shared in this article is based on personal experience and research and is intended for educational purposes only. If you have concerns about your horse‘s health, condition, or treatment, please consult your veterinarian.