Meibomian gland tumors in dogs are benign or malignant tumors stemming from the meibomian glands. The meibomian glands are lined on the eyelid and produce the oil part of the tear film. 

Meibomian gland tumors occur in older dogs over the age of eight. The three most common types are meibomian adenoma, meibomian epithelioma, and meibomian adenocarcinoma.

Eyelid lumps, redness, epiphora, tear stains, eye discharge, dry eye, pain or discomfort, eye rubbing, and behavioral changes are typical signs of a meibomian gland adenoma dog tumor. Tumor ulcers and bleeding are prevalent in cancerous meibomian gland tumor dog cases or adenocarcinoma. 

A veterinarian differentiates between a dog eyelid cyst and a meibomian gland tumor based on appearance, clinical manifestation, and diagnostic procedures like biopsy and FNA. 

The treatment for tumors of the meibomian gland dog tumor is surgical and includes techniques such as wedge resection, blepharoplasty, cryotherapy, or laser ablation. 

What is a Meibomian Gland Tumor in Dogs?

A meibomian gland tumor is a slow-growing tumor that arises from the meibomian gland. The meibomian glands are lined on the eyelid and produce the oily portion of the tear film. The oil prevents tears from evaporating too quickly. 

The most common meibomian gland tumors in dogs are meibomian adenomas (29% to 37%), meibomian epitheliomas (17% to 34%), and meibomian adenocarcinomas (5% to 15%), says a study “The Investigation of Histopathology and Locations of Excised Eyelid Masses in Dogs” published in Veterinary Record Open in 2019. 

Meibomian gland tumors in dogs are common and benign in most cases. The prevalence of benign tumors provides a reliable prognosis. 

The exact cause of meibomian gland tumors as frequent eye condition is unknown. Tumors are generally the result of genetic and environmental factors.  

How does the Meibomian gland Tumor Develop?

The meibomian gland tumor develops when small bumps or overgrowths of blocked oil transform into a tumor. Each dog’s eyelid has dozens of meibomian glands constantly producing oil. The oil sometimes clogs and forms lumps, leading to a dog eyelid cyst. 

Epitheliomas are meibomian gland tumors that arise from the skin or mucosal tissue over the gland. Adenomas (benign) and adenocarcinomas (malignant) stem from the glandular tissue. 

How is Meibomian Gland Tumor Different from Papillomas in Dogs?

A meibomian gland tumor is different from papillomas in dogs in origin, malignancy, appearance, and treatment. 

Meibomian gland tumors are the result of genetic and environmental factors and are common in older dogs. The growths are cobblestone-like in appearance and extend into the eyelid or protrude outward. Meibomian tumors are benign or malignant and require surgical treatment. 

Papillomas are viral and typical in young dogs with compromised immune systems. The growths are smooth or cauliflower-like in texture and grow from the margin of the eyelid. The occurrence of papillomas in dogs is benign and typically resolves independently without treatment. 

What are The Symptoms Of a Meibomian Gland Tumor on A Dog's Eyelid?

The symptoms of a meibomian gland tumor on a dog’s eyelid are listed below. 

• Eyelid Lump: An eyelid lump is the main symptom of a meibomian gland tumor. The lump has a cobblestone surface and varies in color from pink and tan to grey and black. The lump protrudes outward or extends into the eyelid.  
• Redness: Redness is a sign of inflammation and occurs on the conjunctiva in dogs with meibomian gland tumors. The redness indicates that the tumor irritates the surrounding eye tissues, causing inflammation. 
• Increased Tearing: Increased tearing is another consequence of irritation. Tears are protective and aim to flush the eye of the irritant. The medical term for increased tear production is epiphora, which results in watery eyes. 
• Tear Stains: Tear stains develop in dogs that experience increased tearing. The stains form when tears moisten the area beneath the eyes, giving it a red-brownish color. Tear stains occur in all dogs but are most noticeable in white and light-coated dogs. 
• Eye Discharge: Eye discharge forms when the increased amount of tears produced in response to the tumor’s presence mixes with debris and dirt, sheds skin cells, and dries. Eye discharge forms crusts at the corners of the eyes. 
• Dry Eye: Dry eye, or keratoconjunctivitis sicca (KCS), develops when the meibomian gland tumor prevents the eyelid from properly closing. The incomplete closure leaves the eye exposed to air and promotes dryness.  
• Pain or Discomfort: Meibomian gland tumors in dogs are painful. The eyelid’s growth impairs the dog’s vision, causing anxiety on top of the pain and discomfort in severe cases. 
• Eye Rubbing: Eye rubbing is a sign of pain in dogs. Dogs rub their eyes to remove the source of pain and irritation. Eye rubbing is harmful, especially in dogs with bleeding or ulcerating meibomian gland tumors. 
• Behavioral Changes: The behavioral changes stemming from meibomian gland dog tumors include lethargy, reduced energy levels, disinterest in daily activities, loss of appetite, sudden mood swings, and irritability. 

How are Meibomian Gland Tumors Diagnosed in Dogs?

Meibomian gland tumors in dogs are diagnosed based on physical appearance and clinical manifestation. The tumor’s characteristics and accompanying signs and symptoms allow the vet to diagnose presumptively. 

The veterinarian orders specific diagnostic procedures if the mass has an atypical appearance or is suspected to be malignant. 

The most commonly performed diagnostic tests are fine-needle aspiration (FNA) and punch biopsy. FNA collects fluid with a needle and syringe, while punch biopsy takes a tissue sample with a special tool. The samples in both cases are analyzed under a microscope. 

How Does Meibomian Gland Tumor Affect Dogs' Eyelid?

A meibomian gland tumor affects the dog’s eyelid by changing its appearance and function and damaging the eye.  

The meibomian adenoma resembles a cobblestone-surfaced lump with a pink, tan, grey, or black color. The meibomian adenocarcinoma is covered with ulcers and often bleeding. 

Meibomian gland tumors follow the path of least resistance and stem from the eyelid margin. The body of the tumor then follows the eyelid line or protrudes outward compared to the eyelid margin.  

Large meibomian tumors impair the eyelid’s function and prevent it from opening or closing the eye. Dry eye and corneal ulcers are complications when the eyelid is open, and the eye is prone to drying and dehydration. 

Tumors that rub the corneal surface cause irritation and damage. The damage progresses and culminates in ulcers, which are linked to vision deficits. 

Untreated meibomian gland tumors and other eyelid lumps in dogs result in permanent eye damage and vision loss in severe cases. 

What Causes Meibomian Gland Tumors in Dogs?

The causes of meibomian gland tumors in dogs are listed below. 

• Genetic Component: Tumors have a genetic component and are more common in dogs whose progenitors have benign or malignant growths. Eyelid lumps and meibomian gland tumors are widespread in Bulldogs, Bloodhounds, and Cocker Spaniels.  
• Dirt and Debris Accumulation: Dirt and debris accumulation in the eyelids contributes to chalazion or meibomian gland cyst formation. Chalazia increases the risk of meibomian gland tumor development. 
• Meibomian Cysts: Meibomian cysts, or chalazia, are linked to the occurrence of eyelid tumors in dogs. Chalazion in dogs develops when the gland’s duct gets clogged. Dirt, debris accumulation, and increased oil secretion consistency are commonly reported reasons for clogging. 
• Environmental Factors: Environmental factors are critical in tumor formation in dogs. Nutrition, exercise, and sunlight exposure are the most important factors determining tumor emergence. 

How Common Are Meibomian Gland Tumors in Dogs?

Meibomian gland tumors are very common in dogs, accounting for up to 50% of ocular tumors. Meibomian masses are the most common eyelid tumor of middle-aged and older dogs, according to a report on “Meibomian Gland (Eyelid) Tumors in Dogs” by Veterinary Partner in 2021.  

Meibomian gland tumors develop in dogs over eight years old. Benign versions of the tumors are more common than malignant types. 

Dog eyelid masses are between three and eight times more likely to be benign than malignant, reports a study, “The Investigation of Histopathology and Locations of Excised Eyelid Masses in Dogs” published in Veterinary Record Open in 2019. 

Which Breeds Are More Susceptible to Meibomian Gland Tumors?

Bulldogs, Bloodhounds, and Cocker Spaniels are more susceptible to meibomian gland tumors. The high incidence of eyelid tumors in these breeds indicates a genetic predisposition. 

The exact cause of meibomian gland tumor frequency in Bulldogs, Bloodhounds, and Cocker Spaniels is unknown. The eye and facial anatomy of the breeds are unrelated, meaning environmental factors determine tumor development. 

General eye care, exposure to dirt or debris, and lifestyle factors influence the meibomian gland tumor formation in predisposed dog breeds. 

Can Meibomian Gland Tumors in Dogs Be Cancerous?

Yes, meibomian gland tumors in dogs can be cancerous. Cancerous meibomian gland tumors are rare. The two reported types are adenocarcinoma and rarely epithelioma. 

Meibomian adenocarcinoma accounts for 5% to 15% of all eyelid tumors in dogs, according to a study, “Eyelid Neoplasms of Dogs,” published in the American Journal of Veterinary Research in 1975. 

Meibomian adenocarcinomas proliferate, invade the local tissues, and spread to other organs and tissues via the lymph nodes. 

What is the Treatment for Meibomian Gland Tumors in Dogs?

The treatment for meibomian gland tumors in dogs is listed below. 

• Wedge-Resection: Wedge resection is one of the simplest and most used surgical techniques for meibomian gland tumors in dogs. The approach involves making a V-shaped cut around the growth. Wedge resection is indicated for tumors with a large base. 
• Debulking: Debulking is a procedure in which the meibomian gland tumor is cut at the base, and then the wound is closed with sutures or frozen with a cryoprobe. The mix of debulking and cryosurgery is ideal if the tumor is pedunculated or loosely attached to the eyelid base. 
• Blepharoplasty: Blepharoplasty is a reconstruction of the eyelid used in dogs with large or irregularly shaped meibomian gland tumors. The surgical procedure is more complex compared to simple wedge-resection or debulking. 
• Cryotherapy: Cryotherapy is performed with liquid nitrogen and a unique cryoprobe tool. The meibomian tumor is frozen 2-3 times for about 25 to 40 seconds. Cryotherapy is frequently combined with debulking. 
• Laser Ablation: Laser ablation with CO2 is used for meibomian gland tumors with small bases. The use of laser in large-based tumors causes eyelid defects in many cases. The CO2 beam is used as a blade for tumors with large bases, and the wound is traditionally closed. 
• Chemo and Radiation: The veterinarian recommends chemotherapy and radiation for dogs with meibomian adenocarcinomas and cancerous epitheliomas that have spread to other parts of the body. 
• Topical Therapy: Topical therapy is used in the postoperative period to reduce pain and inflammation and promote healing. Topical treatments include artificial tears, antibiotics, and anti-inflammatories. 

Are There Any Home Remedies for Managing Meibomian Gland Tumors in Dogs?

Yes, there are home remedies for managing meibomian gland tumors in dogs. Home remedies are not a substitute for veterinary attention and focus on symptom relief and damage control. 

The home remedy for managing meibomian gland tumors is keeping the eye clean. Use saline or pure water to remove excess tears, discharge, and crusts. 

Use artificial tears and keep the dog’s eye moist and lubricated if the dog’s eyelid does not fully close. Artificial tears are available in the form of eye drops and ointments. 

The Elizabethan collar is another at-home management option for dogs with meibomian gland tumors. The E-collar prevents the dog from rubbing its eyes and causing more damage. Limiting eye access is critical in dogs with ulcerating and bleeding eyelid tumors. 

Use home remedies as a first aid and until veterinary care is provided. Attempting to treat meibomian gland tumors at home delays mainstream treatment, which is detrimental. 

Can Meibomian Gland Tumors in Dogs Cause Vision Problems?

Yes, meibomian gland tumors in dogs can cause vision problems. The tumor scratches the surface of the dog’s eye and irritates it. Minor irritation resolves, but when the scratching persists, it leads to damage. 

A damaged cornea results in vision problems. The problem is more severe when the irritation progresses into an ulcer.  A meibomian gland tumor culminates in vision deficits in a worst-case scenario. 

When Should I Seek Veterinary Care for My Dog's Meibomian Gland Tumor?

You should seek veterinary care for your dog’s meibomian gland tumor as soon as an eyelid lump emerges. 

Eyelid lumps in dogs are slow-growing and take time before causing more significant problems. Schedule an appointment with the veterinarian and monitor the dog carefully. 

See the vet urgently if other worrisome signs and symptoms, such as increased tearing, eye rubbing, or squinting, accompany the eyelid lump. 

Meibomian gland tumors in dogs, especially adenocarcinomas, are prone to forming ulcers and bleeding.