Watery Eyes in Horses: Causes and Treatment

Watery eyes in horses is not uncommon and can look like excessive tearing, discharge, or both. It can be caused by a variety of reasons, ranging from minor irritation to serious health issues.

One of the most common reasons for watery eyes in horses is allergies. Just like humans, horses can be allergic to various substances such as pollen, dust, or mold. These allergens can cause irritation in the eyes, leading to excessive tearing and discharge. Other common causes of watery eyes in horses include infections, injuries, and foreign objects in the eye. It is important to identify the underlying cause of watery eyes in horses to provide appropriate treatment and prevent further complications.

Understanding Watery Eyes in Horses

Watery eyes in horses is a common issue that can be caused by various factors. Just like humans, horses have tear ducts that help to keep their eyes moist and healthy, but when these tear ducts become blocked or infected, the horse can develop watery eyes.

One of the most common causes of watery eyes in horses is allergies. Horses can be allergic to a variety of things, including pollen, dust, and mold. When a horse is exposed to an allergen, their body produces histamines which can cause their eyes to become itchy and watery.

Another common cause of watery eyes in horses is infections. Bacterial and viral infections can cause the tear ducts to become inflamed and blocked, leading to excessive tearing. It is important to treat infections promptly to prevent further complications.

In some cases, watery eyes in horses can be a symptom of a more serious underlying condition, such as equine recurrent uveitis (ERU). ERU is a chronic inflammatory disease that can cause damage to the eyes and lead to blindness.

It is important to consult with a veterinarian if your horse is experiencing persistent watery eyes. The vet can perform a thorough examination and determine the underlying cause of the issue. Treatment options may include medications, eye drops, or surgery, depending on the cause of the watery eyes.

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Common Causes of Watery Eyes

Horses can experience watery eyes due to various reasons. Understanding the common causes of watery eyes in horses allows you to take the necessary steps to prevent or treat the condition. The following are some of the most common causes of watery eyes in horses:

Infections and Inflammations

Infections and inflammations commonly cause watery eyes in horses. Bacteria, viruses, and fungi can cause eye infections, leading to redness, swelling, and discharge. Conjunctivitis, also known as pink eye, is a common bacterial infection that can cause watery eyes in horses. Equine recurrent uveitis is another type of inflammation that can cause watery eyes.

Allergies and Environmental Factors

Allergies and environmental factors can also cause watery eyes in horses. Allergens such as dust, grasses, flies, and insect bites can irritate the eyes, causing them to water. Environmental factors such as scratches, foreign objects, and trauma can also lead to watery eyes.

Injuries and Traumas

Injuries and traumas to the eye can cause watery eyes in horses. Scratching or rubbing the eye can cause inflammation and tearing. Damage to the nasolacrimal ducts or the lacrimal glands can also cause watery eyes.

Other Causes

Other causes of watery eyes in horses include dry eye, corneal ulcers, parasites, and problems with the retina or pupil. In some cases, watery eyes may be a symptom of a more serious underlying condition.

Diagnosis of Watery Eyes

When a horse’s eyes appear watery, it is important to determine the underlying cause in order to provide appropriate treatment. A veterinarian will typically perform a thorough physical examination of the eye, including the cornea, eyelids, conjunctiva, and iris.

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Physical Examination

During the physical examination, the veterinarian will look for any signs of injury or inflammation. They may also use an ophthalmoscope to examine the internal structures of the eye. If necessary, the horse may be sedated to allow for a more thorough examination.

Schirmer Tear Test

The Schirmer tear test is a common diagnostic test used to measure tear production in horses. During the test, a small strip of filter paper is placed in the lower eyelid of the horse for one minute. The amount of tear production is then measured and compared to normal values.

Other Diagnostic Tests

In some cases, additional diagnostic tests may be necessary to determine the underlying cause of watery eyes in horses. These may include:

  • Fluorescein staining to detect corneal ulcers or abrasions
  • Culture and sensitivity testing to identify any bacterial or fungal infections
  • Biopsy of the conjunctiva or eyelid to look for signs of cancer or other abnormalities

Overall, a thorough physical examination and appropriate diagnostic testing are essential for accurately diagnosing the cause of watery eyes in horses. With proper diagnosis and treatment, many cases can be successfully managed without long-term complications such as blindness.

Treatment and Management


When a horse is diagnosed with watery eyes, the veterinarian may prescribe corticosteroids to reduce inflammation in the eye. Topical antibiotics may also be prescribed to treat any underlying bacterial infections. It is important to follow the veterinarian’s instructions carefully when administering these medications, as overuse or misuse can lead to further complications.


In some cases, surgery may be necessary to correct the underlying issue causing the watery eyes. This may involve removing a blockage in the tear ducts or repairing a damaged eyelid. 

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Preventive Measures

Preventive measures can help manage watery eyes in horses. Keeping the horse’s environment clean and free of irritants can reduce the likelihood of inflammation and infection. Regular eye exams can also help catch any issues early on and prevent them from becoming more serious.

Frequently Asked Questions

How to treat a swollen horse eye from flies?

A swollen horse eye from flies can be treated by cleaning the eye with a saline solution and applying a fly repellent ointment to the area. In severe cases, a veterinarian may prescribe medication to reduce inflammation and pain.

What is the most common eye problem in horses?

The most common eye problem in horses is conjunctivitis, also known as pink eye. It is caused by bacterial or viral infections and is characterized by redness, swelling, and discharge from the eye.

How do you know if a horse has a blocked tear duct?

A horse with a blocked tear duct may have excessive tearing, discharge from the eye, and swelling around the eye. A veterinarian can confirm the diagnosis by performing a dye test to see if the tears are draining properly.

What are some equine eye problems?

Equine eye problems include conjunctivitis, corneal ulcers, uveitis, cataracts, and glaucoma. These conditions can cause pain, discomfort, and vision loss in horses.

What can I give my horse for an eye infection with yellow discharge?

A horse with an eye infection and yellow discharge should be seen by a veterinarian for proper diagnosis and treatment. Antibiotics may be prescribed to treat the infection, and the eye should be cleaned regularly with a saline solution.

How do you clear a horse’s tear ducts?

A veterinarian can clear a horse’s tear ducts by flushing them with saline solution or by using a catheter to remove any blockages. In some cases, surgery may be necessary to correct the problem.

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