In the fascinating world of canine companionship, noticing the sudden appearance of your dog's third eyelid can be both intriguing and concerning for many pet owners. This unique feature, often hidden and unnoticed, plays a crucial role in the health and protection of your dog's eyes.

Dr. Diane Hendrix, DVM, DACVO, a leading expert in veterinary ophthalmology and a contributor to groundbreaking research on cherry eye in dogs, emphasizes the importance of understanding the third eyelid's functions and potential issues. In this article, we delve into the anatomy of the canine eye, exploring why the third eyelid might become visible and what it signifies for your pet's health.

Stop Googling - Ask a Real Vet


  1. Do Dogs Have A Third Eyelid
  2. Common Causes of the Third Eyelid's Visibility
  3. Dog Third Eyelid Prolapse
  4. Treatment of the Third Eyelid in Dogs
  5. How Can the Emergency Fund Help with Treatment
  6. FAQs
  7. Conclusion

Do Dogs Have A Third Eyelid

Yes, dogs indeed have a third eyelid, also known as the nictitating membrane. This inner eyelid serves multiple functions, including offering additional protection to the eye's surface, contributing to tear production, and clearing away debris.

Unlike humans, many animals, including dogs, are equipped with this anatomical feature, which remains largely invisible under normal circumstances. The third eyelid is tucked away at the corner of the eye but can sometimes become visible due to various reasons, ranging from relaxation during sleep to health issues.

Observing a noticeable third eyelid can prompt concern, but understanding its purpose and when its appearance might indicate a health problem is crucial for pet owners. Dr. Diane Hendrix, DVM, DACVO, has extensively studied the third eyelid, particularly focusing on conditions like cherry eye, which is when the third eyelid is not only visible but red and inflamed. Her research, available for in-depth reading here, provides valuable insights into the prevalence, treatment, and management of third eyelid protrusions in dogs.

For those concerned about their dog's third eyelid visibility or any related eye issues, keeping an eye on your pet's health has never been easier with the help of technology like the Petcube Camera. This device not only allows pet owners to monitor their pets remotely but also to spot any unusual behaviors or signs of discomfort that may warrant a closer look or a consultation with a veterinarian.

Why Is My Dog's Third Eyelid Showing

The sight of your dog's third eyelid prominently showing can be a source of alarm, prompting immediate concerns about their overall eye health, according to veterinary sources on canine ophthalmology. This condition, where the third eyelid, also referred to as the nictitating membrane, becomes visible, can be triggered by a variety of factors, ranging from minor irritations to more serious health issues. Understanding why your dog's third eyelid is showing is crucial in determining the appropriate course of action and ensuring the well-being of your canine companion.

Common Causes of the Third Eyelid's Visibility

Irritation or Injury

One of the most straightforward reasons the third eyelid becomes visible is due to irritation or injury to the eye. Whether from dust, debris, or a scratch from rough play, the third eyelid may protrude as a protective response to help heal and shield the eye.

Inflammation or Infection

Conditions such as conjunctivitis (pink eye) or other infections can cause inflammation, making the third eyelid more noticeable. Redness, discharge, and your dog squinting or pawing at their eye are common signs of these conditions.


Just like humans, dogs can suffer from allergies that affect their eyes, leading to the third eyelid showing. Allergens in the environment, such as pollen, dust, or certain foods, can trigger allergic reactions, resulting in eye irritation and the prominence of the third eyelid.

Haw Syndrome

Also known as "cherry eye," this condition specifically affects the gland of the third eyelid, causing it to swell and become visible. Though it is not painful, it can lead to further complications if left untreated.

Neurological Issues

The third eyelid's appearance can sometimes indicate neurological problems, where nerve damage or dysfunction affects the eye's normal position or the eyelid's ability to retract.

General Illness

Systemic diseases, such as certain viral infections or even dehydration, can lead to the third eyelid showing. This is often accompanied by other symptoms, such as lethargy, loss of appetite, or fever.


Physical trauma to the head or eye area can result in the third eyelid becoming visible. This could be the result of a direct blow, a fall, or a confrontation with another animal.

When to Seek Veterinary Attention

While the occasional glimpse of the third eyelid in one or both eyes might not always signify a serious problem, consistent visibility, especially if accompanied by redness, discharge, or behavioral changes (like lethargy), warrants a visit to the veterinarian. Early diagnosis and treatment can prevent more severe complications and ensure your dog's health and comfort. Conditions such as "cherry eye," infections, or allergies can often be treated effectively with medication or, in some cases, surgery.

Dog Third Eyelid Prolapse

A specific condition that often raises concern among pet owners is the prolapse of the third eyelid, commonly referred to as "cherry eye." Unlike other reasons for the third eyelid showing, a prolapse occurs when the gland of the third eyelid, responsible for a significant portion of tear production, becomes dislodged from its normal position. This results in a distinctive, cherry-like swelling at the eye's corner, which, while not immediately harmful, can lead to long-term issues if left untreated.

Understanding Third Eyelid Prolapse

The third eyelid plays a critical role in maintaining eye health by providing additional protection and lubrication. When the gland prolapses, it can lead to decreased tear production, resulting in dry eye (keratoconjunctivitis sicca) or secondary infections due to inadequate protection and lubrication of the eye surface.

Causes and Risk Factors

While the exact cause of third eyelid gland prolapse is not fully understood, it is believed to be related to weak connective tissue within the eyelid. Certain breeds, such as Bulldogs, Beagles, and Cocker Spaniels, are more predisposed to this condition, suggesting a genetic component.

Treatment Options for Canine Cherry Eye

Treatment typically involves surgical repositioning of the prolapsed gland. Early intervention is crucial to prevent permanent damage to the gland and ensure it continues to function properly. In some cases, if left untreated, removal of the gland may become necessary, though this is not ideal as it increases the risk of dry eye syndrome.

Monitoring Your Dog's Eye Health

Regular check-ups and vigilant observation of your dog's eye health are essential. Any signs of discomfort, excessive tearing, or redness should prompt a visit to the veterinarian. For pet owners, maintaining a watchful eye over their pets, even when you're not physically there, is made easier with technologies like the Petcube Camera. This device allows you to monitor your pet's well-being remotely, ensuring that any signs of eye discomfort or other health issues can be addressed promptly, providing peace of mind and the best possible care for your pup.

Treatment of the Third Eyelid in Dogs

The appearance of the third eyelid in dogs can signal various conditions, each requiring a specific approach to treatment. Addressing third-eyelid issues promptly is crucial for maintaining your dog's eye health and overall well-being. Here's an overview of the treatment options based on the underlying cause:

Surgical Intervention for Cherry Eye

When dealing with a third eyelid prolapse, or "cherry eye," surgical repositioning of the prolapsed gland is the most common treatment. This procedure aims to restore the gland to its original location, preserve its function, and prevent future complications. Veterinarians often recommend surgery as the most effective way to deal with this condition, ensuring the third eyelid can continue to protect the eye and produce tears normally.

Managing Infections and Inflammation

If the third eyelid becomes visible due to an infection or inflammation, treatment may include antibiotics or anti-inflammatory medications. Topical ointments or drops are commonly prescribed to alleviate symptoms and address the underlying issue. In cases of allergic reactions causing the third eyelid to show, antihistamines or other allergy treatments can help reduce symptoms.

Addressing Underlying Health Conditions

For third-eyelid visibility resulting from systemic health issues, treating the primary condition is essential. This could involve a broader range of diagnostics and treatments, depending on the diagnosis. Regular veterinary check-ups and monitoring are key to identifying and managing such health concerns.

How Can the Emergency Fund Help with Treatment

Facing unexpected health issues with pets can be daunting, especially when considering the potential costs involved. The Petcube Emergency Fund is designed to alleviate these worries, covering up to $3000 in emergency vet bills per year for about $1 a day. This includes access to 24/7 online vet care, offering immediate assistance whenever you need it. Whether it's surgical intervention for a prolapsed third eyelid, treatment for infections, or managing other acute health issues, the Emergency Fund ensures your pet can receive the necessary care without delay.

For readers of this blog, an exclusive 27% discount on the Emergency Fund is available through this special link. This offer makes it even more accessible for pet owners to enjoy peace of mind, knowing that they're prepared for any emergencies that may arise, ensuring the best possible care for their beloved pets.


Why does my dog's third eyelid show when they are sleeping?

It's common for dogs' third eyelids to become visible while they are sleeping. This phenomenon occurs because, during sleep, dogs' eyes can partially roll back, exposing the third eyelid. This protective membrane helps keep the eye moist and free from debris while your dog rests. It's a normal physiological response and usually not a cause for concern.

What does it mean if my dog's third eyelid is covering their eye?

If your dog's third eyelid is covering their eye, it could be a sign of irritation, injury, or a more serious health issue. This condition, known as "cherry eye" when the gland of the third eyelid prolapses, requires veterinary attention. Other causes might include infections, inflammation, or neurological issues, all warranting a professional evaluation.

Will my dog's third eyelid issue go away on its own?

Some minor third-eyelid issues, such as temporary exposure due to sleep or slight irritation, may resolve on their own. However, persistent visibility, especially if accompanied by signs of discomfort or other symptoms, likely requires veterinary intervention. Conditions like cherry eye or significant infections will not resolve without treatment and may worsen over time.

How much does surgery for a dog's third eyelid cost?

The cost of surgery for a dog's third eyelid, such as corrective surgery for a cherry eye, can vary widely depending on the location, the severity of the condition, and the veterinary clinic. Generally, pet owners can expect the cost to range from several hundred to over a thousand dollars. It's best to consult with your veterinarian for a more accurate estimate tailored to your dog's specific needs.


Noticing your dog's third eyelid can be an unexpected discovery, but understanding the reasons behind its visibility is crucial for maintaining your pet's eye health. From the protective role it plays during sleep to the need for surgical intervention in cases like cherry eye, the third eyelid is an essential part of your dog's ocular anatomy.

Was this article helpful?

Help us make our articles even better

Yes No

Thank you for your feedback