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Tumor of the Eye in Dogs

Uveal Melanoma in Dogs

Dogs can develop uveal melanoma, a type of tumor that affects the uvea, comprising the iris, ciliary body, choroid, and pars plana. Melanoma, characterized by the malignant growth of melanocytes containing melanin pigment, primarily manifests in the front of the iris, extending to the ciliary body and choroid. Unlike intraocular melanomas, which appear as raised masses, uveal melanomas are typically flat and diffuse initially, exhibiting a benign appearance.

Uveal melanomas are the most prevalent primary intraocular neoplasms in dogs, predominantly affecting the anterior uvea. While these tumors are usually unilateral and benign, they have the potential to cause severe damage to the eye. Approximately four percent of anterior uveal melanomas metastasize through the bloodstream to the lungs and other visceral organs, posing a risk of cancerous spread. Choroidal melanomas, on the other hand, seldom metastasize. Understanding these characteristics is crucial for diagnosing and managing uveal melanoma in dogs effectively.


Anterior Uveal Melanoma:

  • Presence of pigmented mass on the sclera (white part of the eye) or cornea (the transparent front part of the eye)
  • Visible pigmented mass
  • Irregular pupil
  • Inflammation of the uvea
  • Increased pressure in the eyes (Glaucoma)
  • Blood in the eye (Hyphema)
  • Vision loss only if the mass obstructs the pupil or if glaucoma develops

Choroidal Melanomas:

  • Often overlooked due to the tumor’s location deeper in the eye
  • Mass situated farther back in the eye
  • Characterized by slow growth, seldom requiring eye removal
  • Considered a rare tumor

Understanding these symptoms and types is essential for identifying and addressing uveal melanoma in dogs promptly.


  • The exact cause is unknown.
  • Flat, pigmented iris freckles may have the potential to develop into melanomas.
  • There is a presumed autosomal (non-sex-linked) recessive inheritance pattern observed in Labrador retrievers.

Understanding these causes is vital for further research and the development of effective strategies for the prevention and management of uveal melanoma in dogs.


Your veterinarian will conduct a comprehensive physical examination of your dog, including a thorough ophthalmic assessment to evaluate eye pressure and drainage of aqueous humor. A complete blood profile, comprising a chemical blood profile, complete blood count, urinalysis, and electrolyte panel, will also be performed. Evidence of metastasis may appear in the blood profile, while an increased white blood cell count could indicate the immune system’s response to malignant cell growth. Providing a detailed history of your dog’s health and symptom onset is crucial.

X-rays and ultrasound imaging may aid in assessing the extent of metastatic disease in the eye. During the ophthalmic examination, tonometry will measure eye pressure, while gonioscopy will determine if the melanoma has spread to the drainage angle. Slit-lamp biomicroscopy enables evaluation of the mass’s size and location. Transillumination, utilizing strong light to shine through the eyeball, may assist in diagnosis. Indirect ophthalmoscopy may also be used to examine the eye, with or without scleral indentation. These diagnostic procedures are essential for accurately diagnosing and assessing uveal melanoma in dogs.


Uveal melanomas in dogs are typically benign tumors that do not spread. Monitoring the eye for changes every 3–6 months is an option. However, young Labrador retrievers, particularly prone to rapidly growing uveal melanomas, may require surgical intervention. Enucleation, or removal of the affected eye, is the recommended treatment.

Indications for enucleation include rapid increase in mass size, inability to salvage the eye, diffuse spread of the mass within the eye, significant impairment of visual function, tumor invasion outside the eye, and the presence of secondary complications such as glaucoma, signs of pain, or bleeding.

Understanding these treatment options and indications is essential for effectively managing uveal melanoma in dogs, ensuring the best possible outcome for their health and well-being.

Living and Management

Enucleation, or removal of one eye, is typically performed to preserve the health of the remaining eye. Animals adapt remarkably well to being one-eyed, adjusting quickly to changes in visual capacity. However, if your dog develops glaucoma as a result of uveal melanoma, they may experience significant pain. Symptoms such as head shaking, head pressing, whining, pawing at the head, lethargy, and slow movements may indicate discomfort and should be promptly addressed.

Your veterinarian will schedule follow-up appointments for X-ray and ultrasound imaging at six and twelve months post-surgery or treatment. During these appointments, the enucleation site will be evaluated, and checks for tumor recurrence or metastasis will be conducted. Regular monitoring and management are crucial for ensuring your dog’s continued well-being and addressing any potential complications effectively.

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