Background: Interest in meibomian gland dysfunction (MGD) is growing in veterinary medicine. However, research on MGD in dogs is lacking. The aims of this study were to compare the interferometry grades, tear meniscus height (TMH) and non-invasive tear break-up time (NIBUT) grades between dogs with and without MGD. Methods: Routine ophthalmic examination, interferometry, NIBUT assessment, TMH measurement and meibography were performed. Age and Schirmer tear test-1 (STT-1) results were compared between the control and MGD groups using Student's t-test. Interferometry grades, NIBUT grades and TMH were compared between the two groups using Mann-Whitney U-test. Results: There was no significant difference in age between the two groups (p = 0.279). STT-1 (p = 0.024), interferometry (p = 0.004) and NIBUT grades (p = 0.012) were significantly lower in the MGD group than in the control group. No significant difference in TMH values (p = 0.587) was observed between the two groups. While the control group included 18 and seven eyes in meiboscore 0 and 1, in MGD group, 12, eight, five and three eyes were included in meiboscore 0, 1, 2 and 3, respectively. Conclusions: Low interferometry and NIBUT grades were associated with MGD, suggesting decreased meibum and disrupted tear film quality. TMH did not differ between the two groups. Meibography could aid in the diagnosis of MGD in severe cases, although it could not detect early MGD in the dogs in this study.

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.