Signalment information, determined by physical examination and client supplied information, was recorded for each dog included in the infection group of the study. Complete ocular examination, including slit lamp biomicroscopy, indirect ophthalmoscopy (Heine EN20-01 indirect ophthalmoscope; Heine Optotechnik, Herrsching, Germany), fluorescein staining (Fluor-I-Strips; Schering-Plough Animal Health Co., Union, NJ), and Schirmer I tear testing (Schirmer tear test strips; Schering-Plough Animal Health Co.) were performed on each dog with ocular disease. For eyes with ulcerative keratitis, a corneal ulcer scoring system was used to quantify biomicroscopy findings. The following variables were scored for each eye: corneal ulcer area (defined as area of fluorescein retention relative to total corneal area): 0 = <25%, 1 = 26% to 50%, 2 = 51% to 75%, 3 = >76%; corneal ulcer depth (defined as deepest point of the ulceration relative to total corneal depth): 0 = <25%, 1 = 26% to 50%, 2 = 51% to 75%, 3 = >76%; anterior chamber reaction: 0 = none, 1 = mild aqueous flare, 2 = moderate-to-marked aqueous flare, 3 = hypopyon; corneal edema area relative to total corneal area: 0 = <25%, 1 = 26% to 50%, 2 = 51% to 75%, 3 = >76%; corneal leukocyte infiltration: 0 = none, 1 = mild, 2 = moderate, 3 = severe; and keratomalacia: 0 = none, 1 = mild, 2 = moderate, 3 = severe.