Two different procedures for managing ocular melanosis presenting scleral pigmentation with glaucoma in a Shih-Tzu dog: A case of definitive diagnosis in one eye and a presumed diagnosis in the contralateral eye

Abstract

A 12-year-old castrated male Shih-Tzu dog was referred for uncontrolled glaucoma and uveitis with highly pigmented sclera, in both eyes (OU). On ophthalmic examination, the menace response, dazzle reflex and pupillary light reflex were negative OU. The intraocular pressure was 27 mmHg in the right eye (OD) and 70 mmHg in the left eye (OS) despite the administration of antiglaucoma eyedrops. Ultrasound biomicroscopy revealed a closed ciliary cleft OU. Ocular ultrasonography revealed hyperechoic materials in the vitreous OU and retinal detachment OS. When presented for recheck, an extensive malacic corneal ulcer was observed OS. To relieve pain in the blind eyes, enucleation OS and pharmacologic ciliary body ablation (CBA) OD were performed. Histologically, ocular melanosis, which is an inherited disease in the Cairn Terrier breed, was identified in the enucleated eye. The uvea was heavily pigmented. The iris and ciliary body were mildly distorted by a single population of large, round, nonneoplastic cells with pigmented cytoplasm. There was no evidence of an intraocular mass or metastasis before and after intravitreal CBA. This is the first report of bilateral ocular melanosis in a Shih-Tzu dog. Ocular melanosis is a possible differential diagnosis for globe presenting scleral pigmentation with glaucoma in even non-Cairn Terrier breeds and pharmacologic CBA could be considered as a treatment for ocular melanosis with end-stage glaucoma.

Keywords: Cairn Terrier; Shih-Tzu; ciliary body ablation; ocular melanosis; scleral pigmentation.