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Background

The eyelid margin is the edge of the eyelid where the eyelid touches the colored part of the eye. The eyelid margins of dogs, cats, and people are made of tissues including skin, oil glands, and an inner lining similar to the gums inside the mouth.

The inner lining of the eyelid is called the conjunctiva. The oil glands are called meibomian glands and are a type of sebaceous gland. The oil produced is part of the tear film that lubricates the eyes and helps them stay moist.

Each eyelid contains dozens of these glands.

Eyelid margin masses can be found inside or outside the eyelid and are visible without special medical equipment. Their color can vary, ranging from tan to pink-red to black.

Eyelid masses can develop from infections, tumors, or cancers. Some eyelid margin masses have a mixture of these problems. Eyelid infections may be combined with eyelid tumors, cancers or vice versa.

Infections

The meibomian glands can become blocked by abnormal oils, leading to the development of an eyelid mass. Dogs with allergies are more likely to develop abnormal meibomian gland oil. Build-ups of abnormal oil can become infected with bacteria, and the resulting infections can quickly worsen or cause large areas of the eyelids to swell. Squinting or rubbing at the eyelids are common symptoms.

Rupture of meibomian gland material into the surrounding tissues can trigger an inflammatory reaction, leading the mass to suddenly enlarge and become more irritated.

Tumors

Sometimes tumors develop in the meibomian glands or the skin of the eyelid margin, leading to a mass. Eyelid margin tumors are typically seen in older dogs and are most often benign. These benign tumors can grow slowly or rapidly. If the eyelid margin tumor touches the surface of the eyeball, it can be uncomfortable, scratch the eye, or prevent the eye from shutting correctly. These tumors can become irritated, leading to pain.

Gland tumors are the most common type of eyelid tumor in middle-aged and older dogs, with the average age at onset being eight years old.

Cancer

While most eyelid masses are due to infection or benign tumors, some may be malignant cancer. Eyelid margin cancer may develop from eyelid skin, muscles, connective tissues, blood vessels or meibomian glands. Eyelid cancer can damage bones and other tissues around the eye or spread to other parts of the body like the lymph nodes or lungs.

Cancer can sometimes spread from another part of the body to the eyelids. Telling eyelid cancers apart from tumors or infections is not always possible just by looking at them.

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What to Watch For

If an eyelid mass is smaller than a pencil eraser and doesn’t change in size, color, or shape, the mass may be a cosmetic issue but should still be monitored. Some eyelid tumors may resolve on their own within two months. Consider photographing the eyelid mass over time to help detect small changes.

If the mass is larger than the tip of a pencil eraser, it could cause damage to the eye itself, and in severe cases, can cause an ulcer on the eye. Large eyelid masses that are wider than a penny are more likely to cause injury or could cause problems with blinking. If an eyelid mass is larger than the tip of a pencil eraser, see your veterinarian.

If you have any suspicion that an eyelid mass is growing, changing or causing pain, see your veterinarian.

Treatment

Eyelid masses from infection are treated with eye drops, eye ointments, or oral medications.  Sometimes treating an infection around a tumor or cancer can reduce the size of the mass.

Cryosurgery

Small eyelid masses may be treated with surgical removal or cryosurgery. Cryosurgery involves freezing the mass to try to kill the tumor or cancer cells in the eyelid under general anesthesia. Cryosurgery will treat the local cancer but not metastasis. The goal of surgery is to remove a tumor or cancer cells from the body. Removal of a tumor may be the best way to ensure it doesn’t come back. Freezing may be the only treatment or used in addition to surgery, depending on the size and location of the eyelid mass. 

The surgical approach depends on the details and location of the mass.  Sutures will close the incision. Large eyelid masses may be biopsied before other treatments are planned to determine if the mass is an infection, a tumor, or cancer. Large eyelid masses may also be surgically removed, but the surgery may be more complicated.

Any removed mass should be submitted for pathology to determine if it’s benign or malignant.

Malignant cancer may need additional eye or body treatment, especially if the cancer has spread to or comes from other parts of the body.

After surgery, your dog will likely need to wear an E-collar to prevent them from irritating the incision. No matter which method is used to remove an eyelid margin mass, the swelling from surgery will resolve in about two weeks.

Prevention

Sun exposure can cause eyelid skin cancer, particularly in animals with white skin and hair around the eyes. If your dog has white color around the eyes, try to limit direct sun exposure as much as possible.

It is not known why dogs get eyelid tumors or cancers, nor can they be prevented. You can check your dog’s eyes yourself to look for signs of a problem. Discuss any questions or concerns you may have with your veterinarian.