If you’ve ever owned or loved a horse, you know how much they mean to us. Horses aren’t just animals – they’re loyal companions, partners in sport, and in many cases, members of our family. That’s why hearing about diseases like Equine Infectious Anemia (EIA) can feel so worrying.

So, what actually causes this condition? And why do vets take it so seriously? Let’s break it down in simple terms.

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The Culprit: A Sneaky Virus

Equine Infectious Anemia is caused by a virus – specifically, the Equine Infectious Anemia Virus (EIAV). It’s part of the same family of viruses that cause HIV in humans, but don’t worry – it only affects horses, mules, and donkeys.

📌 Related Reading: How to Keep Your Horse Healthy Year-Round

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How Does It Spread?

EIA isn’t passed from horse to horse through casual contact like sharing a pasture or standing near each other. Instead, the virus needs a little “help” to move around – and that help comes from blood-feeding insects like horseflies and deerflies.

Here’s how it usually happens:

• A fly bites an infected horse and picks up some of its blood.
• That same fly then bites another horse within a short time.
• With that bite, the virus is injected into the healthy horse’s bloodstream.

📌 For a detailed explanation, you can check the USDA’s guide on Equine Infectious Anemia.

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Why It’s So Serious

The disease can appear in different ways:

• Some horses get very sick, showing fever, weight loss, weakness, and anemia.
• Others may recover but still carry the virus for life.
• A few don’t show any outward signs but remain infectious to others.

Because of these “carrier horses,” controlling EIA is extremely challenging. That’s why testing – often called the Coggins test – is so important for horse owners.

📌 Learn more: What is a Coggins Test and Why Every Horse Needs It?

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What Horse Owners Can Do

While there’s no cure or vaccine yet, there are steps every owner can take to protect their horses:

1. Regular Testing – Have your horse tested annually, especially if you travel or compete.
2. Fly Control – Reduce the number of biting flies around your stable with proper waste management, fly sprays, and physical barriers.
   👉 Check this helpful resource: Effective Fly Control Strategies for Horses
3. Responsible Horse Management – Avoid sharing needles or equipment that can transfer blood.
4. Know the Rules – Many states and countries require proof of a negative Coggins test for transport or events.

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Final Thoughts

Equine Infectious Anemia is caused by a virus that spreads through blood – usually with the help of biting flies. While that sounds scary, understanding the cause helps us take the right precautions. With good testing, fly control, and responsible care, we can protect our horses and keep this silent threat under control.

Remember, awareness is the first step toward prevention. As horse lovers, our best defense is staying informed and acting responsibly.

📌 You might also like: Top 10 Common Horse Diseases Every Owner Should Know

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Frequently Asked Questions About Equine Infectious Anemia

1. What is the main cause of Equine Infectious Anemia?

Equine Infectious Anemia is caused by the Equine Infectious Anemia Virus (EIAV), which spreads mainly through biting flies like horseflies and deerflies.

2. Can Equine Infectious Anemia spread directly from horse to horse?

No. EIA does not spread through casual contact such as sharing pasture or touching noses. It usually requires blood transfer via biting insects or contaminated equipment.

3. Is there a cure for Equine Infectious Anemia?

Unfortunately, there is no cure or vaccine available yet. Once a horse is infected, it carries the virus for life.

4. How can I protect my horse from EIA?

You can protect your horse by scheduling regular Coggins tests, practicing good fly control, and avoiding the sharing of needles or equipment.

5. Why is the Coggins test important?

The Coggins test helps detect EIA in horses, including those that don’t show symptoms but can still spread the virus. It’s required for travel, shows, and sales in most countries.