Characterisation of corneal impression cytology in dogs and its application in the diagnosis of keratoconjunctivitis sicca.

Objective: Determine morphological and morphometric parameters of corneal epithelium in dogs, and determine the cellular alterations that occur in canine keratoconjunctivitis sicca (KCS) using impression cytology.

Study Animals: 60 dogs divided into two groups: dogs with Schirmer tear test (STT) at least 15 mm/minute and absence of ocular disease, and dogs with STT less than 15 mm/minute and clinical signs of KCS.

Procedures: Impression cytology was used to collect corneal samples. The percentage of eyes with cell changes, the number of such cells and the percentage of cells with structural alterations in each group were determined. The possible correlation between corneal epithelium alterations and decreased tear production was evaluated.

Results: A significant positive correlation existed between STT and the area of the cytoplasm and nucleus of corneal cells. A significant negative correlation was found between STT ​​and the nucleus/cytoplasm ratio, and the presence of cellular changes. A significant difference existed between the numbers of pyknotic nuclei, being higher among animals with all stages of KCS.

Conclusion: Corneal impression cytology can be used to assess the corneal epithelium in healthy eyes and eyes with KCS, demonstrating its usefulness as a diagnostic tool especially in mild and early cases.