Ophthalmic examination findings of Thoroughbred racehorses in Australia.

The research article presents a prospective study on eye diseases in Thoroughbred racehorses in Victoria, Australia. The article has drawn attention to the prevalence of vision-threatening diseases in this equine population and emphasizes the relevance of ocular examination in routine physical check-ups of horses.

Research Methodology

• The study involved 204 Thoroughbred racehorses from four metropolitan and two country racing stable complexes.
• Each horse was subjected to an ophthalmic examination after dark adaptation. Tools used for the examination included a transilluminator, biomicroscope, and direct ophthalmoscope.
• Intraocular pressures were measured where deemed necessary.
• Both pupils of the horses were dilated with a drug known as tropicamide for specific cases.

Findings of the Study & Examination

• The participants comprised of 182 (89.2%) flat-racing horses and 22 (10.8%) jump-racing horses. The maximum and minimum ages were nine and two years respectively, with the average age being 3.7 years.
• Among the horses, 97 (47.5%) were neutered males, 74 (36.3%) were females and 33 (16.2%) were males.
• Potentially vision-threatening diseases were found in 15 (7.4%) horses. These included complete lenticular cataracts, posterior lens luxation and cataract, significant peripapillary ‘butterfly’ lesions (both active and inactive) and optic nerve atrophy.
• Non-vision-threatening eye diseases were recorded in 57.4% of the horses. These ranged from eyelid scars, corneal scars, corporal band opacity, peripapillary chorioretinal lesions to anterior iris synechia and developmental cataracts.
• Unusual variations of normal ocular anatomy and colobomata were found in 11 (5.4%) different horses. These anomalies included granular iridica hypoplasia, granular iridica hyperplasia, multilobular granular iridica cyst, microcornea, hyaloid remnant, rotated optic nerve head, coloboma of the lens and atypical coloboma of the retina.

Conclusion & Implications

• The study unveils a potentially high prevalence of vision-threatening eye diseases among Thoroughbred racehorses, suggesting that the numbers may be much higher than what is generally perceived.
• This highlights the importance of regular ocular examinations in the routine physical evaluation of horses to prevent or treat potential vision-threatening conditions early on.