Ocular abnormalities in a herd of Old Kladruber Horses: A cross-sectional study

To screen a closed herd of the Old Kladruber Horses (OKH) for the prevalence of ocular disorders and report normal ocular variations.

Two hundred and sixty-one horses, 122 Old Kladruber Gray Horses, and 139 Old Kladruber Black Horses owned by the National Stud Farm Kladruby nad Labem, Czech Republic, were included in the study with signalment and pedigree information recorded.

Bilateral ocular examination of manually restrained horses was performed in a darkened environment by a single examiner (RA), using a portable slit-lamp biomicroscope, direct ophthalmoscope, and monocular indirect ophthalmoscopy using a Finnoff transilluminator and 20 D condensing lens. Fluorescein testing was performed when indicated.

The animal ages ranged from 3 months to 27 years (mean 7.82 years, median 6 years). The gender ratio (males:females) was 109:152. Ophthalmological abnormalities were found in 133 (50.96%) horses; with right and left eyes affected equally. The most common abnormalities were cataract formation (35 horses), iris hyperpigmentation (29 horses), alterations in corpora nigra size (26 horses), nonsenile vitreal degeneration (24 horses), linear keratopathy (11 horses), corneal stromal haze (nine horses) and corneal subepithelial punctate opacities (nine horses). The most frequent variations of normal ocular anatomy were posterior lenticular suture lines (222 horses), tapetal hypoplasia (95 horses) resulting in a multi-colored tapetal fundus (31 horses), nuclear sclerosis (48 horses), and senile vitreal degeneration (30 horses).

Ocular disorders were relatively common in OKH, but typically not vision threatening and not interfering with the quality of life.