Intraocular melanoma in a horse

Area of Science:

• Veterinary Ophthalmology
• Equine Pathology
• Ocular Oncology

Background:

• Uveal nevi are common in horses and can potentially transform into melanomas.
• Intraocular melanomas can cause significant vision impairment and ocular disease.

Observation:

• A 7-year-old Quarterhorse presented with sudden unilateral blindness.
• Ophthalmoscopy revealed a pigmented mass originating from the nasal ciliary body, extending to the lens and vitreous.
• Histopathology of the enucleated eye confirmed a malignant intraocular melanoma with invasion.

Findings:

• The mass was composed of heavily pigmented, polyhedral cells invading ocular tissues.
• The tumor exhibited sessile attachment to the ciliary body and extended to the retina and optic papilla.
• The diagnosis was primary, malignant, intraocular melanoma arising from a uveal nevus.

Implications:

• This case underscores the potential for uveal nevi to develop into aggressive melanomas in horses.
• Early detection and understanding of equine ocular tumors are crucial for diagnosis and treatment.
• Further research into the pathogenesis and treatment of equine intraocular melanomas is warranted.