Characterization of cells collected from nasolacrimal duct flush samples in healthy rabbits (Oryctolagus cuniculus)

Abstract

Nasolacrimal duct flushing is frequently performed on domestic rabbits (Oryctolagus cuniculus) with ocular and/or upper respiratory system clinical signs, including epiphora or dacryocystitis, seen secondary to dental disease. This procedure is technically straightforward, requires minimal equipment, and can be both diagnostically and therapeutically useful. Cytological quantification of nasolacrimal duct flushes of healthy rabbits has not been reported previously. Cytocentrifuged preparations of nasolacrimal duct flushes from ten, young, clinically healthy, female intact white New Zealand rabbits (n = 20 eyes) were reviewed. Total nucleated cell count was estimated as 500 cells/L. When cellularity was appropriate, 100-leukocyte and 500-epithelial cell differentials were performed. Epithelial cells were characterized as anucleated keratinized squamous cells, nucleated keratinizing squamous cells, intermediate cells, columnar cells, and goblet cells. The bacterial population was cytologically characterized. Four samples were removed due to poor cellularity; the rest were subsequently analyzed independently (n = 16). No significant difference was detected between ducts within each animal for heterophil percentage (P = 0.37), lymphocyte percentage (P = 0.5), or large mononuclear cell percentage (P = 0.58) using a paired t-test. The mean ± SD for heterophil, lymphocyte, and columnar cell percentages were 56.4 ± 31.5%, 29.5 ± 26.3%, and 30.9 ± 23.6%, respectively. The median for large mononuclear, anucleated-keratinized, nucleated, intermediate, and goblet cell percentages were 8% (2–39%), 16.7% (7.8–63.7%), 18.4% (4.2–65.8%), 2.4% (0–9.4%), and 1.7% (0–61.8%), respectively. In the epithelial cell differential, columnar cells were found in the highest percentages compared to the rest of the cell types. The results presented in this study demonstrate that the typical cellularity in the nasolacrimal duct of healthy rabbits has heterophils in higher percentages and an absence of other polymorphonuclear cells.