The iris is the most common origin of primary intraocular tumors in all species of domestic animals. The iris is the most common site of origin for ocular melanocytic (brown pigmented) tumors in canine and feline species. Feline diffuse iris melanoma is the most common type of ophthalmic melanoma (cancer) in cat species, with an average onset age of 11 years. FDIM begins as concentrated or multiple areas of iridal pigmentation that gradually increase in size.
The progression rate of FDIM is highly variable and the disease can have long dormant periods. FDIM can be metastatic (spreading of the tumor to the rest of the body) in felines and may spread to the lung, spleen, liver and other parts of the abdomen. This unpredictability makes it challenging for Veterinary Ophthalmologists to offer advice on when best to remove the affected eye, which may still provide vision.
Photographing the affected eye over time intervals is a very helpful way to document growth of the lesion, iridal pigmentation change, and changes in anterior chamber depth. Other diagnostic options include a full body X-ray to rule out the metastasis and a full blood panel to establish a baseline.
Laser therapy is not recommended for iris melanoma in cats owing to their higher metastatic potential.Back to Previous Page