Visible Third Eyelid in Dogs (Cherry Eye): Definition, Cause, and Treatment

A visible third eyelid is a condition in which the third eyelid pops from its hidden position in the inner corner of the eye and becomes visible. 

The third eyelid (nictitating membrane) protects the eye from debris, acting like a curtain or windshield wiper. 

The third eyelid is normally visible in dogs during sleep or post-nap. A visible third eyelid under other circumstances indicates a health problem. 

Health issues leading to visible third eyelids are common in brachycephalic breeds due to their large, bulging eyes and shallow eye sockets. 

Eye irritation, injuries, inflammation, infection, eyelid cartilage eversion, prolapsed eyelid gland, neurological conditions, and dehydration make the dogs 3rd eyelid visible. A prolapsed gland or cherry eye is the most common cause of a visible dog third eyelid. 

The treatment for a visible third eyelid dog ranges from topical eye drops to surgery based on the underlying cause. 

Cherry eye is always treated surgically. The surgery aims to reposition the gland and restore the dog third eyelid normal functionality. 

CBD oil for dogs is a beneficial addition to the dogs third eyelid management plan. Pet CBD oil is natural and safe for dogs of all breeds and ages. 

What is Visible Third Eyelid in Dogs?

Visible third eyelid in dogs is a condition in which the hidden third eyelid becomes visible. The third eyelid protects the eye from abrasions and moistens the eyeball by evenly distributing tears. 

The third eyelid comprises a thin membrane lined with conjunctiva, a T-shaped cartilage, and a tear gland held in position by the cartilage. 

Diseases affecting the eye and systemic illnesses irritate and make the third eyelid visible. Cherry eye is the most common cause of visible third eyelids. 

Cherry eye, or prolapsed nictitating membrane gland (PNMG), is a widespread eye problem in dogs. 

One in 500 dogs develops cherry eye, and brachycephalic breeds are 6.9 times more prone to cherry eye compared to other dogs, according to a study titled “Breed and Conformational Predispositions for Prolapsed Nictitating Membrane Gland (PNMG) in Dogs in the UK” by the Royal Veterinary College’s VetCompass Programme in 2022.  

Cherry eye makes the third eyelid visible temporarily or permanently, depending on the severity. Dogs with mild forms have their eyelids tucked in, which pop out under pressure when the dog is sneezing, coughing, or defecating. 

A permanently exposed third eyelid is more troublesome than a temporary one. The eyelid irritates the surface of the eyeball if it grows large enough. Long-term irritation leads to corneal damage and ulcers. 

How does the third eyelid in dogs Work?

The third eyelid in dogs works like a windshield wiper. The primary role of the third eyelid is to clear the cornea (the transparent layer that covers the eyeball and inside the eyelids). 

The third eyelid features a T-shaped cartilage structure beneath its conjunctival cover. The T-shaped cartilage resembles a glass cleaning wiper. The third eyelid sweeps back and forth across the eye surface, wiping off mucus and debris and distributing tear film.  

The third eyelid’s function is compromised when the eyelid becomes visible. A visible third eyelid is addressed through topical or surgical means, depending on the underlying cause. 

How many eyelids do dogs typically have?

Dogs typically have three eyelids. The three eyelids are the upper (superior), lower (inferior), and third (nictitans or nictitating membrane) eyelid. 

The upper and lower eyelids are easily visible, and the third eyelid is typically hidden in the inner corner of the eye in healthy dogs. 

The third eyelid differs from the upper and lower eyelids in structure. The eyelid resembles a membrane lined with conjunctival tissue. 

The nictitating membrane, or third eyelid, is present in all dogs. The only variations between breeds are in eyelid size and pigmentation. 

The third eyelid was present in humans but shrank in size and lost functionality due to evolution, becoming a structure called the plica semilunaris (half-moon fold). 

How is the Visible Third Eyelid Different from Eyelid Lumps?

A visible third eyelid is different from eyelid lumps in etiology, appearance, and treatment, but the two conditions are similar in effect. A visible third eyelid and lumps cause eye irritation and damage in more severe cases.  

The visible third eyelid is caused by irritation, inflammation, injury, or neurological issues. The eyelid protrudes from the inner corner of the eye. The treatment options vary from eye flushing to surgical correction.

Eyelid lumps are caused by blocked meibomian glands (chalazion) and tumors (meibomian adenomas, meibomian epitheliomas, meibomian adenocarcinomas, papillomas, or melanomas). 

The lumps are pendant-shaped with large bases, smooth or cobblestone-like, and range from pink and tan to grey and black. Eyelid lumps in dogs require surgical correction by a veterinarian.

Why do some dogs have a visible third eyelid?

Some dogs have a visible third eyelid due to their facial anatomy. The third eyelid is more visible in brachycephalic or flat-faced dogs compared to dolichocephalic (long-faced) breeds. 

Brachycephalic breeds have large, bulging eyes and naturally small, shallow eye sockets. The facial characteristics make the third eyelid more pronounced and visible. 

Brachycephalic dogs include Pugs, Bulldogs, Boxers, Pekingese, Boston Terriers, Shih Tzus, Lhasa Apsos, and Cavalier King Charles Spaniels. 

Are visible third eyelids in dogs a cause for concern?

Yes, visible third eyelids in dogs are a cause for concern. The third eyelid is usually hidden in healthy dogs with correct eye anatomy. 

Certain eye or eyelid conditions and systemic diseases cause the third eyelid to protrude and become visible. A dog with a visible third eyelid warrants veterinary attention. 

A visible third eyelid in dogs is normal only when the dog falls asleep, sleeps with partially closed eyes, and immediately after waking up. 

Can a dog's third eyelid indicate health issues?

Yes, a dog’s third eyelid can indicate health issues. A conscious dog's visible third eyelid gland points to eye conditions or general diseases. 

Infections, inflammation, and membrane prolapse are common eye conditions causing visible third eyelids. Dehydration is a systemic condition resulting in a visible third eyelid. 

Eye health issues progress quickly and go from bad to worse in days. Consult a veterinarian if the dog’s visible third eyelid persists. 

What conditions may cause a dog's third eyelid to be Visible?

The conditions that may cause a dog’s third eyelid to be visible are listed below. 

• Eye Irritation and Injury: Eye irritation and traumatic eye injuries cause the third eyelid to emerge and become visible. Allergic dermatitis, dust, and sand are dogs' most common causes of eye irritation. Traumatic eye injuries occur during rough play with other pets. 
• Eye Inflammation or Infection: Inflammatory and infectious conditions of the eye result in the visible third eyelid. Conjunctivitis is a prevalent eye infection and is bacterial, viral, or fungal. The third eyelid protrudes in eye inflammation and infection cases to shield the eye and help it heal. 
• Third Eyelid Gland Prolapse: Prolapsed nictitating membrane gland (PNMG) or cherry eye is a condition in which the third eyelid gland protrudes. The protrusion makes the third eyelid visible and resembles a cherry in the dog’s inner eye corner. Cherry eye is frequent in brachycephalic dog breeds. 
• Third Eyelid Cartilage Eversion: Third eyelid cartilage eversion occurs when the front and back cartilage forming the third eyelid grow at different rates. Eversion is widespread among large and giant dog breeds like Weimaraners, Great Danes, Dobermans, and German Shepherds. 
• Neurological Conditions: Horner syndrome is the most common neurological condition with a visible third eyelid in dogs. The exact cause of the condition is unknown. Horner syndrome is common in Doberman Pinschers, Labrador Retrievers, Weimaraners, Shetland Sheepdogs, and Golden Retrievers. 
• Severe Dehydration: Dehydrated dogs have visible third eyelids. Systemic diseases such as infectious illnesses and hormonal imbalances cause dehydration. 

How is a prolapsed third eyelid treated in dogs?

A prolapsed third eyelid in dogs is treated surgically. The treatment aims to reposition the gland back into its third eyelid pocket and ensure normal function (tear production). 

Several surgical procedures are available, with the Morgan pocket technique (MPT) being the most commonly used treatment. 

The Morgan pocket technique was first described in a 1993 study, “Prolapse of the gland of the third eyelid in dogs: a retrospective study of 89 cases (1980 to 1990),” published in the Journal of The American Animal Hospital Association. 

Veterinarians today use an updated version of the modified Morgan pocket technique. The procedure involves making two ecliptical and parallel incisions in the eyelid’s conjunctiva to create a pocket and repositioning the gland into the pocket. 

Eye drops are used pre and post-surgery to manage the symptoms. The vet prescribes artificial tears to keep the eye moist, anti-inflammatories to reduce inflammation, and antibiotics to control eye infections. 

Wearing an Elizabethan collar and limiting strenuous activities (running and jumping) during the postoperative period is critical to recovery. 

Dogs prone to cherry eye and dogs with a history of third eyelid gland prolapse must avoid wearing tight collars during walks. Replace the collars with harnesses to prevent pressure and reduce the risk of the gland popping out of its eyelid pocket. 

What is the typical appearance of a dog's third eyelid?

The typical appearance of a dog’s third eyelid is a hidden membrane with varying size and pigmentation. 

The normal eyelid is tucked away in the inner corner of the eye, called the medial canthus. The eyelid is triangular and made of a thin layer of membrane lined with conjunctiva. 

The size of the third eyelid depends on the dog’s size. The color ranges from pink to brown or black-pigmented, based on the dog’s color. 

Do all dog breeds have a visible third eyelid?

No, not all dog breeds have a visible third eyelid. The third eyelid is a universal feature for all dogs. A healthy, normal third eyelid is hidden underneath the dog’s eye glands and is not visible. 

Brachycephalic dogs have a more visible third eyelid than other breeds. The presence of a visible third eyelid is problematic and requires veterinary attention.  

What role does the nictitating membrane play in a dog's eye anatomy?

The nictitating membrane plays a protective role in a dog’s eye anatomy. The third eyelid provides physical and chemical protection. 

Physical protection is supplied by wiping dirt and debris from the eye's surface and covering it during injury. 

For example, when the eye is in danger of trauma, the retractor bulbi muscle pulls it deep into the socket. The eyelid rolls over the eye like a curtain to protect its delicate composition.  

The third eyelid chemically protects the eye by bearing the third eyelid gland, which produces 50% of the dog’s tears. The third eyelid’s tissue secretes immunologic agents that fight off infections. 

Will my puppy's third eyelid go away?

No, your puppy’s third eyelid will not go away. The third eyelid is a normal anatomical structure. The causes of visible third eyelids in puppies sometimes resolve on their own. 

For example, a visible third eyelid caused by allergic conjunctivitis disappears if the allergen exposure is limited or periodic. 

The third eyelid remains visible until correctly treated in puppies with cartilage eversion. Cherry eye-associated visible third eyelids come and go periodically. 

What triggers cherry eye in dogs?

The triggers of cherry eye in dogs are listed below. 

• Ligament Problems: Cherry eye occurs when the ligament holding the third eyelid in place breaks or is stretched and overly mobile. The exact reason why ligament issues in dogs develop is unknown. 
• Strong Emotions: Intense feelings, like stress and excitement, trigger the third eyelid gland to prolapse in dogs with loose ligaments. The gland is usually concealed, but when strong emotions occur, it pops up and becomes visible. 
• Genetics: Cherry eye is prevalent among certain breeds, such as the Neapolitan Mastiff, Lhasa Apso, English Bulldog, American Cocker Spaniel, Shih-Tzu, Boston Terrier, Bloodhound, and Shar Pei. 
• Selective Breeding: “Artificial selection for extreme facial characteristics in dogs” is linked to high risk of corneal ulcers and cherry eye, suggests a study, “Impact of Facial Conformation on Canine Health: Corneal Ulceration,” published in PlosONE in 2015. 
• Age Predisposition: Prolapsed third eyelid gland is possible in dogs of all ages, but it is the most common among puppies and young dogs less than two years of age. 

Can CBD Oil Help Reduce Visible Third Eyelids in Dogs?

Yes, CBD oil can help reduce the visible third eyelid in dogs. CBD helps with the underlying causes and symptoms of the visible third eyelid while veterinary treatment is pursued. 

CBD, or cannabidiol, is a natural hemp extract. Cannabidiol has anti-inflammatory, analgesic, and calming properties. 

CBD's anti-inflammatory effect helps decrease inflammation, common in dogs with prolapsed third eyelids. The analgesic feature relieves pain. 

The calming potential keeps dogs relaxed and prevents the eyelid from popping out due to strong emotions. CBD’s relaxing effect keeps dogs calm during the postoperative period.