While the term "cherry eye" is commonly used to describe a specific eye condition in dogs, horses do not develop classic "cherry eye" in the same way.
What is Horse Cherry Eye?
In the context of horses, "cherry eye" is a misnomer because they do not experience the blockage or prolapse of the third eyelid gland that defines the condition in dogs. Unlike canine "cherry eye," which is typically a primary eye problem involving the gland itself, a visible or protruding third eyelid in a horse is almost always a symptom of an underlying health issue.
Why Horses Don't Get "Cherry Eye"
The classic "cherry eye" condition in dogs refers to the prolapse (popping out) of the gland of the third eyelid (nictitating membrane). This gland, located at the inner corner of the eye, becomes swollen and red, resembling a small cherry. In horses, the anatomy and function of the third eyelid gland differ, and they do not typically suffer from this specific type of glandular blockage or prolapse.
What a Protruding Third Eyelid Means in Horses
Although horses don't get "cherry eye," you might observe their third eyelid becoming more prominent or partially covering the eye. This is a significant clinical sign that indicates a problem elsewhere in the horse's body or a serious eye condition. Protrusion of the third eyelid is often a reflex to pain or discomfort, or a symptom of systemic illness.
Common reasons a horse's third eyelid might be visible include:
- Pain or Discomfort: Any painful condition affecting the eye itself, such as an ulcer, foreign body, or inflammation (uveitis), can cause the third eyelid to protrude as a protective mechanism.
- Systemic Diseases: Severe body-wide diseases are a common cause. A prime example is tetanus, a serious bacterial infection that affects the nervous system and can cause muscle spasms leading to third eyelid protrusion.
- Dehydration or Weight Loss: In some cases, significant dehydration or severe weight loss can cause the eye to sink into the orbit, making the third eyelid appear more prominent.
- Neurological Issues: Conditions affecting the nerves controlling the eye or surrounding muscles can lead to a visible third eyelid.
Distinguishing Features: Dogs vs. Horses
Understanding the fundamental differences between the conditions often mistakenly grouped under "cherry eye" can be helpful:
Feature | Dogs (Classic "Cherry Eye") | Horses (Protruding Third Eyelid) |
---|---|---|
Condition Type | Primary eye gland prolapse | Symptom of an underlying problem, not a specific eye gland issue |
Appearance | Red, fleshy mass (prolapsed gland) at the inner corner of the eye | The pale third eyelid itself becomes visible or covers part of the eye |
Underlying Cause | Weak connective tissue holding the gland in place | Variety of issues, often systemic (body-wide) or severe eye pain |
Common Examples | Brachycephalic breeds (e.g., Bulldogs, Beagles, Boston Terriers) | Tetanus, eye pain, dehydration, severe systemic disease |
Treatment Focus | Surgical repositioning of the gland | Diagnosing and treating the root cause of the protrusion |
When to Seek Veterinary Attention
If you notice your horse's third eyelid becoming more visible or protruding, it is a serious sign that warrants immediate veterinary attention. Prompt diagnosis and treatment of the underlying cause are crucial to ensure your horse's well-being and prevent potential complications. A veterinarian will conduct a thorough examination of the eye and the horse's overall health to determine the root cause of the protrusion.