Uveal Melanoma in Dogs (Choroidal Melanoma)

  • Occurrence: rarer
  • Location of disease: Head/Neck
Author: Dr. med. vet. Gisa Löwe | Last modified: 02.06.2026
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When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

?

If the condition worsens / symptoms persist, consult a veterinarian.

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Definition

A choroidal melanoma, also known as uveal or choroidal melanoma, is a rare but potentially malignant tumor that occurs in dogs and develops from the pigmented cells of the eye’s choroid.

The most important facts at a glance

Uveal or choroidal melanoma is a rare tumor in dogs that arises from the pigmented cells of the choroid in the eye. These cells contain melanin, which gives the eye color and protects it from harmful light. The exact causes are not fully understood, but genetic factors and possibly environmental factors such as sun exposure may play a role. Symptoms may include changes in iris color, distorted pupils, Inflammatory conditions, increased intraocular pressure, and visual impairment. Diagnosis requires thorough examinations by a veterinarian, often using ophthalmoscopy, ultrasound, biopsy, and imaging procedures such as MRI or CT scans.

Treatment depends on tumor size and stage and may include surgical removal, radiation therapy, or laser therapy. In advanced cases, chemotherapy may be necessary. The prognosis varies depending on the tumor stage and whether metastases are present. With early diagnosis and treatment, the prognosis is more favorable. Regular follow-up examinations are important to monitor for recurrence or spread of the tumor.

Prevention measures are limited because the causes are not fully understood. Regular veterinary check-ups and possibly protection from UV radiation may help. Owners should watch for symptoms so they can act early.

Causes

The choroid is part of the middle layer of the eye, known as the uvea. It consists of pigmented cells that contain melanin, which gives the eye its color and protects the inside of the eye from harmful light. However, these cells can become abnormal, similar to skin cells, and develop into a melanoma. In dogs, melanoma in the choroid is rare, but the condition can have serious consequences.

The exact causes of uveal melanoma are not yet fully understood. Genetic factors are thought to play a role, as certain dog breeds are affected more often. Environmental factors, such as excessive sun exposure, may also play a role, although this is less clear in dogs than in humans.

Mutations in cells play a crucial role in the development of melanoma. These genetic changes can occur spontaneously or be caused by external influences. Research is investigating whether certain genes or genetic markers are associated with an increased risk of this type of tumor in dogs.

Symptoms

Rare symptoms:

An early sign of choroidal melanoma can be a change in eye color or the appearance of dark spots on the iris. These changes are often subtle and can easily be overlooked.

More advanced symptoms may include swelling of the eye, redness, pain, or irritation. The dog may start rubbing the affected eye or squinting. In some cases, vision loss or displacement of the eyeball may occur.

Because these symptoms can also occur with other eye diseases, it’s important to seek a veterinary examination if choroidal melanoma is suspected.

Diagnosis

Diagnosing uveal melanoma requires a thorough examination by a veterinarian, ideally one who specializes in eye diseases. An ophthalmoscope can be used to inspect the inside of the eye and look for signs of a tumor.

Additional diagnostic tests may include ultrasound examinations of the eye to determine the size and exact location of the tumor. A biopsy may also be performed, in which a small sample of the tumor tissue is taken and examined under a microscope to confirm the diagnosis.

Imaging procedures such as MRI or CT scans can be used to determine whether the melanoma has spread to other parts of the body.

Therapy

Treatment for choroidal melanoma depends on the size and stage of the tumor. In some cases, surgical removal of the tumor may be necessary. This may include enucleation (removal of the eye), especially if the tumor is very large or vision has already been irreversibly damaged.

Radiation therapy can be used for smaller tumors to destroy the cancer cells without having to remove the eye. A newer option is laser therapy, which targets the tumor while sparing the surrounding healthy tissue.

In some cases, chemotherapy may be considered, especially if the tumor has metastasized. The choice of treatment depends on many factors, including the dog’s overall health and the owner’s preferences.

Prognosis and follow-up care

The prognosis for a dog with choroidal melanoma depends on various factors, including the size and location of the tumor, whether the tumor has spread, and how early it was diagnosed. With early diagnosis and treatment, the prognosis can be positive, especially if the tumor has not yet metastasized.

However, if the tumor has spread to other parts of the body, the prognosis worsens significantly. Regular follow-up examinations are important to monitor for recurrence of the tumor or spread.

The dog’s quality of life is an important factor that must be considered when deciding on treatment. Some treatments can have significant side effects that may affect the animal’s well-being.

Prevention

Because the exact causes of choroidal melanoma are not fully understood, there are no specific prevention measures. However, general preventive care and regular veterinary check-ups can help detect changes in the eye early.

For dogs that spend a lot of time outdoors, protecting the eyes from excessive UV radiation may be sensible, although this has been studied less in relation to preventing eye tumors in dogs. Dog sunglasses or avoiding intense sunlight could theoretically reduce the risk.

Educating owners about the possible signs of choroidal melanoma is also important so they can act quickly at the first signs of changes.

Frequently asked questions (FAQs)

1. What is choroidal melanoma in dogs?
Choroidal melanoma (uveal melanoma) is a tumor arising from the pigmented cells of the choroid, iris or ciliary body. It is the most common primary eye tumor in dogs. The tumor usually grows slowly and, unlike in humans, often shows benign behavior.
2. What symptoms appear?
Typical signs are dark patches or nodules on the iris that grow over weeks to months. Other signs include irregular pupil shape, changes in eye color, secondary glaucoma, uveitis or bulging of the eye. Owners may also notice lens displacement or hemorrhage in the eye.
3. Which dogs are more often affected?
Middle-aged to older dogs are predisposed, particularly Labrador Retrievers, Golden Retrievers and German Shepherds. There is no clear sex preference. The tumor is rare in young dogs but does occur.
4. How is the diagnosis made?
Ophthalmic examination with slit lamp and ophthalmoscopy often reveals the tumor directly. Ocular ultrasound (B-mode) and, if needed, MRI or CT are used to assess extent. Definitive diagnosis usually requires histology after enucleation.
5. Is uveal melanoma malignant?
In dogs, the majority of uveal melanomas are benign or low-grade malignant. Metastases are rare and most often involve the liver. Mitotic rate, location (ciliary body more aggressive than iris) and extension beyond the eye determine prognosis.
6. How is the disease treated?
Small superficial iris tumors may be treated with laser photocoagulation or local resection without sacrificing the eye. With advanced tumors, secondary glaucoma or rapid growth, enucleation (removal of the eye) is the treatment of choice. Adjuvant chemotherapy is reserved for rare aggressive forms.
7. Does the dog lose much quality of life after enucleation?
Dogs usually compensate very well for the loss of one eye and need only a few weeks to adapt. Their vision in the remaining eye and their other senses are very capable. Quality of life generally remains intact.
8. How high is the metastatic risk?
Studies indicate that about five percent of uveal melanomas in dogs metastasize, particularly those with higher mitotic rate or extraocular spread. Follow-up with abdominal ultrasound and thoracic radiographs every six months for two years is advisable.
9. Can choroidal melanoma stop growing spontaneously?
Very small iris melanomas occasionally remain stable for years. As long as they remain small, painless and do not impair vision, close observation with regular follow-up is acceptable. Once growth begins, intervention is indicated.
10. How does choroidal melanoma differ from eyelid melanoma?
Choroidal melanomas arise within the eye and are predominantly benign in dogs. Eyelid melanomas occur on the eyelid skin and are also usually benign. Oral and digital melanomas in dogs, by contrast, are highly malignant and frequently metastasize, with markedly worse prognosis.