If your veterinarian has told you that your dog has cancer of the eye, you're probably feeling scared, overwhelmed, worried and confused. What are dog tumors of the eye, what causes them and what sort of treatment can help? This information will help you understand this condition and what your veterinarian can do.
What are Melanocytic Eye Tumors?
Melanocytes are simply cells that make melanin, a pigment, and melanocytic tumors are formed by abnormal melanocytes. Melanoma (also called malignant melanoma or melanosarcoma) is a tumor that spreads, while melanocytoma refers to benign, non-spreading tumors.
The most common types of dog tumors of the eye are those that start in the iris, and they usually start out as benign. Eyelid, limbal, choroid and conjunctival tumors are rare, and only conjunctival tumors are malignant.
What Causes Dog Cancer?
The causes for dog cancer of any kind are not very straightforward, just as with people. While humans often develop melanoma through environmental and host factors, dogs with a lot of pigmentation are most affected by tumors. Your dog's genetic makeup and heavy pigmentation is probably the biggest predisposing factor.
Symptoms of an Eye Tumor in Your Dog
Not all tumors of the eye will be apparent, or display symptoms. When symptoms are present, you may notice the following:
• Blood in the eye
• Increased pressure in the eye (glaucoma)
• Inflammation of the eye
• Irregular pupil
• A visible pigmented (colored) mass
• Pigmented mass on the scheral (white part of the eye) or corneal (transparent part of the eye) area of the eye
• Bulging or sunken eye
Diagnosis of Canine Eye Tumors
Tumors of the eye are usually visible using an ophthalmoscope. Accurate diagnosis, however, depends upon a microscopic examination of the tissue, and your veterinarian may use a couple methods to get a tissue sample, such as a biopsy, cellular aspirate or full excision.
How are Dog Eye Tumors Treated?
Melanocytic tumors in dogs that show in different parts of the eye require different treatment. With conjunctival tumors, which are typically malignant, dog eye surgery is the treatment of choice to remove the entire eye. Limbal tumors are also treated with dog eye surgery, but this option allows for surgical excision without removing the entire eye. Some tumors in dogs require more extensive surgery.
Surgery is still the best option for tumors, and there hasn't been much progress with other types of treatments. Sometimes chemotherapy is recommended for certain types of cancer in dogs, such as intraocular lymphosarcoma.
Prognosis
Unfortunately, pain is common with dogs with cancer, and some types of tumors cause more pain than others. Untreated, tumors will decrease your pet's quality of life and prolong recovery and treatment.
The prognosis for your dog will depend on the type of eye tumor they have, and how soon it's discovered and treated. Eyelid tumors, for example, are usually benign and have an excellent prognosis, while the prognosis for malignant tumors is more guarded.
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