Why High Eosinophils in a Horse Can Be a Sign of Parasites or Stomach Problems

When you get your horse’s blood work done, one of the things that might catch your vet’s eye is a high eosinophil count. Eosinophils are a type of white blood cell that play a role in your horse’s immune system. But when their numbers rise, it often signals that something is wrong. Two common causes are parasites and stomach problems. Understanding why this happens can help you take better care of your horse and catch issues early.

What Are Eosinophils and Why Do They Matter?

Eosinophils are part of the immune system. They help fight off certain infections, especially those caused by parasites. They also respond to allergic reactions and inflammation. Normally, eosinophils make up a small percentage of the white blood cells in your horse’s bloodstream.

When eosinophil levels rise, it means the body is reacting to something. This reaction can be due to parasites living inside the horse or inflammation in the stomach or intestines. High eosinophils are a clue that your horse’s immune system is working hard to fight off a problem.

How Parasites Cause High Eosinophils

Parasites are a common cause of high eosinophil counts in horses. These unwanted guests live inside the horse’s digestive system or other tissues. They irritate the body and trigger an immune response.

Common Parasites Linked to High Eosinophils

• Strongyles: These worms live in the intestines and can cause damage to the lining, leading to inflammation.

• Bots: Larvae of bot flies attach to the stomach lining, causing irritation.

• Roundworms (Ascarids): Mostly a problem in young horses, they can cause digestive upset and immune reactions.

• Pinworms: These cause itching around the tail but can also raise eosinophil levels.

  
  
  
  

When parasites invade, eosinophils increase to attack and help remove them. This immune response can cause symptoms like weight loss, poor coat condition, colic, or diarrhea.

Managing Parasites to Control Eosinophils

Regular deworming is key to keeping parasite levels low. However, overusing dewormers can lead to resistance. It’s best to use targeted treatments based on fecal egg counts. This approach helps reduce parasites while avoiding unnecessary medication.

One product that supports parasite control is EquiGuard Dewormer. It offers broad-spectrum protection against common equine parasites and is designed to be gentle on your horse’s system. You can learn more about it here.

Stomach Problems That Raise Eosinophils

High eosinophils can also point to stomach or intestinal issues. These problems cause inflammation, which triggers the immune system to send more eosinophils to the affected area.

Eosinophilic Gastritis and Enteritis

Eosinophilic gastritis and enteritis are conditions where eosinophils build up in the stomach or intestines. This buildup causes swelling, pain, and digestive problems. Horses with these conditions may show signs like:

• Poor appetite

• Weight loss

• Colic or abdominal discomfort

• Diarrhea or loose stools

  
  
  
  

The exact cause is not always clear but may involve allergies, parasites, or other irritants. Diagnosing these conditions usually requires blood tests, ultrasound, and sometimes biopsy.

Supporting Digestive Health

To help manage stomach problems, feeding a balanced diet and reducing stress is important. Some supplements can support gut health and reduce inflammation.

Close-up view of a horse’s stomach area showing healthy coat and skin

How to Know When to Test for Eosinophils

If your horse shows signs like weight loss, poor coat, colic, or changes in appetite, it’s a good idea to get a blood test. A complete blood count (CBC) will show eosinophil levels and help your vet understand what might be going on.

Regular health checks and fecal egg counts can catch parasite problems early. If stomach issues are suspected, your vet may recommend ultrasound or endoscopy.

What You Can Do to Protect Your Horse

• Schedule regular veterinary check-ups and blood tests.

• Perform fecal egg counts to monitor parasite levels.

• Use targeted deworming products like EquiGuard Dewormer.

• Support digestive health with supplements such as GastroCare Plus.

• Provide a balanced diet and clean water.

• Watch for signs of discomfort or changes in behavior.

  
  

Taking these steps helps keep your horse healthy and reduces the chance of problems that cause high eosinophils.

Eye-level view of a horse grazing in a green pasture with clear sky

High eosinophils are a warning sign. They tell us the horse’s body is fighting something. Parasites and stomach problems are common causes. By understanding this, you can act quickly to protect your horse’s health.

If you want to learn more about managing your horse’s health, including parasite control and digestive support, check out the resources and products available at First Choice Equine. They offer trusted solutions to help you keep your horse in top condition.

Taking care of your horse means paying attention to the signs. High eosinophils are one of those signs. With the right knowledge and tools, you can keep your horse healthy and happy for years to come.