Dry-eye syndrome in Shih Tzu dog: Ocular surface clinical and morphological aspects in the different stages of keratoconjunctivitis sicca

ABSTRACT: This study analyzed clinical and cyto-histomorphological parameters of the ocular surface of Shih Tzu dogs, non-carriers and carriers of quantitative keratoconjunctivitis sicca (KCS) at different stages. Thirty-five eyes from 23 male and female Shih Tzu dogs between two and eight years were evaluated in four groups: control group (CG - without KCS), mild KCS group (KCS1), moderate KCS group (KCS2), and severe KCS group (KCS3). Most clinical variables among KCS carrier groups worsened at the more advanced stages of the disease, with a negative correlation between the Schirmer tear test (STT-1) and tear film break-up time (TBUT). Squamous metaplasia, lymphoplasmacytic inflammatory infiltrate, and decrease in conjunctival goblet cells on histopathological examination comprised disease severity parameters. Quantitative KCS non-carried Shih Tzu dogs have qualitative and tear film distribution changes. The cytomorphological exam is limited to evaluating the inflammatory infiltrate and quantifying conjunctival goblet cells. However, intermediate epithelial cells were higher in healthy eyes compared to eyes with KCS in Shih Tzu dogs. Also, moderate and severe KCS carrier Shih Tzu dogs have qualitative dysfunction of the tear film. KCS in Shih Tzu dogs is common and chronic and may be responsible for the loss of vision of these animals. Early identification of the disease and routine evaluation can improve these dogs’ quality of life and ocular health.