A study on the morphoquantitative and cytological characteristics of the bulbar conjunctiva of the maned wolf (Chrysocyon brachyurus; Illiger, 1815).

The maned wolf, Chrysocyon brachyurus, is a near-threatened carnivore inhabiting the Brazilian Cerrado. Few studies have been conducted on this species, and even fewer have explored its ophthalmological characteristics. Vision is critical to wild canids; thus, this study aimed to provide a morphoquantitative description of the bulbar conjunctiva of the maned wolf using cytological and histological analyses. Ten healthy maned wolves from a conservational centre, including 4 females and 6 males aged 1-12 years (6.5 ± 2.8), were included in the study. The samples for cytological analysis were collected from the inferior conjunctival sac using a cytobrush, and conjunctival tissue was collected for histological analysis from the temporal canthus zone. The cytological samples were stained using the Papanicolaou method, and the histological sections were stained using haematoxylin and eosin, Periodic acid-Schiff, picrosirius red and Masson's trichrome stains. The cytological samples were studied for stain quality, and the different cell types were counted. Histological examination was used to determine tissue types in the conjunctiva and their proportions. Analyses revealed a stratified squamous epithelium with some goblet cells and eventual pigmentation in the basal layer. Loose connective tissue with the presence of some mononuclear and polymorphonuclear cells was also observed. The epithelium of the maned wolf's bulbar conjunctiva resembles that of dogs and other carnivore species; furthermore, its physiological and pathological responses were similar to those of other carnivore species.