Ophthalmic contributions to assessing eyes of two neotropical canids: Cerdocyon thous and Chrysocyon brachyurus.

Objective: To describe selected ophthalmic tests and anatomical features of eyes of crab-eating foxes (Cerdocyon thous) and maned wolves (Chrysocyon brachyurus).

Animals Studied: Six crab-eating foxes (12 eyes), eight maned wolves (16 eyes).

Procedures: Intramuscular and/or inhalatory anesthesia, ophthalmic evaluation with portable slit-lamp biomicroscope, Schirmer tear test (STT), intraocular pressure measurement with rebound and applanation (crab-eating fox only) tonometers, measurement of palpebral fissure length (PFL), gonioscopy, and fundoscopy. Data were analyzed with ANOVA and Tukey's tests.

Results: Both species presented upper and lower eyelids, both with eyelashes and Meibomian glands openings. A third eyelid was also present. In partial miosis, pigmented projections were observed along the edge of the pupil. The draining angle was open, with thin pectinate ligaments. The retina was holangiotic. For crab-eating foxes, mean ± standard deviation values were as follows: STT: 4.33 ± 2.96 mm/min; PFL: 17.45 ± 1.55 mm; rebound tonometry: 10.70 ± 3.43 mm Hg (TonoVet calibration D),5.66 ± 3.44 mm Hg (TonoVet calibration P), 17.00 ± 4.64 mm Hg (TonoVet Plus calibration dog); and applanation tonometry: 11.70 ± 5.70 mm Hg(TonoPen XL). For maned wolves, the mean ± standard deviation values were as follows: STT: 9.31 ± 7.40 mm/min; PFL: 22.79 ± 1.63 mm; rebound tonometry: 11.00 ± 2.77 mm Hg (TonoVet calibration D), 6.78 ± 2.58 mm Hg (TonoVet calibration P), and 18.29 ± 3.47 mm Hg(TonoVet Plus calibration dog).

Conclusions: This study contributes with knowledge that can help the clinical assessment regarding eyes of crab-eating foxes and maned wolves. The data herein presented for rebound tonometry are new for both species.