A survey of ocular pathology in Warmblood horses in South Africa.

Background: Warmblood horses are a popular breed around the world for equestrian sports. Previous studies have investigated ocular findings in other breeds of horses; however, no studies exist for the Warmblood breed.

Objectives: To determine the prevalence of ocular abnormalities in a convenience sample of Warmblood horses in South Africa and to determine if the prevalence of lens and chorioretinal lesions increase with age.

Study design: Descriptive, observational study.

Methods: Warmblood horses underwent a full ophthalmic examination which included a Schirmer tear test (STT), tonometry, fluorescein dye testing, slit lamp biomicroscopy and indirect ophthalmoscopy. Age was categorised into three groups namely <8 years old, 8-13 years old and 14+ years old for statistical analysis. Prevalence of lens and chorioretinal lesions were compared between age categories.

Results: One hundred and four horses (208 eyes) were examined. The age range was 5 months to 30 years (mean 11 years, standard deviation [SD] 6 years). Ocular pathology was noted in 125 eyes (60.1%) and 79 horses (76%). The highest number of lesions were noted in the choroid and retina, iris and lens. Chorioretinal lesions were seen in 100 eyes (48.1%) and in 65 horses (62.5%). Iridial lesions were seen in 19 eyes (9.1%) and 12 horses (11.5%). Cataracts were seen in 19 eyes (9.1%) and in 13 horses (12.5%). The presence of total chorioretinal lesions (eye level [p = 0.002]; horse level [p = 0.004]), focal chorioretinal lesions (eye level [p = 0.004]; horse level [p = 0.008]) and cataract (eye [p = 0.03]; horse level [p = 0.02]) were all shown to statistically increase with age.

Main limitations: A small sample size and limited geographic area.

Conclusions: There was a high prevalence of ocular pathology in this population of Warmblood horses in South Africa. This reiterates the importance of an ocular examination as a part of routine health checks, as well as during prepurchase examinations.