Ocular findings in a population of geriatric equids

Though eye lesions were common in this set of geriatric horses they did not seem to have a significant effect on vision.
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Ocular findings in a population of geriatric equids in the United Kingdom
Equine Vet J. 2023 Apr 18. doi: 10.1111/evj.13941. Online ahead of print.
Authors
Ria Chalder 1 , Nicola Housby-Skeggs 2 , Claire Clark 2 , Danica Pollard 3 , Claudia Hartley 1 , Benjamin Blacklock 1
Affiliations

1 The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK.
2 The Horse Trust, Slad Lane, Princes Risborough, UK.
3 The British Horse Society, Kenilworth, UK.

Abstract
in English, German

Background: There are a growing number of horses, ponies, and donkeys aged 15 years or older in the United Kingdom, yet there have been no studies utilising a complete ophthalmic examination to investigate the prevalence of ophthalmic pathology within this population.

Objectives: To investigate the prevalence of ophthalmic pathology and associations with signalment, in a convenience sample of geriatric equids in the United Kingdom.

Study design: Cross sectional.

Methods: Horses, ponies, and donkeys aged 15 years or older based at The Horse Trust charity underwent a full ophthalmic examination including slit lamp biomicroscopy and indirect ophthalmoscopy. Relationships between signalment and pathology were assessed using Fisher’s exact and Mann-Witney U tests.

Results: Fifty animals were examined ranging from 15 to 33 years (median 24, interquartile range [IQR] 21, 27). The prevalence of ocular pathology was 84.0% (95% confidence interval [CI] 73.8, 94.2%; n = 42). Four animals (8.0%) had adnexal pathology, while 37 (74.0%) and 22 (44.0%) had at least one form of anterior or posterior segment pathology, respectively. Of those with anterior segment pathology, 26 animals (52.0%) had cataract in at least one eye, with the most common location being anterior cortical (65.0% of those animals with cataract). Animals with posterior segment pathology included 21 animals (42.0%) with fundic pathology, with senile retinopathy being the most common (42.9% of all animals with fundic pathology). Despite the high prevalence of ocular pathology, all eyes examined remained visual. The most common breeds were Irish Draught (24.0%, n = 12), Shetland (18.0%, n = 9) and Thoroughbred (10%, n = 5); the majority were geldings (74.0%, n = 37). There was a statistically significant relationship between the presence of anterior segment pathology and breed (p = 0.006), with all Cobs and Shetlands examined having anterior segment pathology. The presence of posterior segment pathology and senile retinopathy were associated with older median age (posterior segment pathology: 26.0 years [interquartile range {IQR} 24.0, 30.0 years] vs. 23.5 years [IRQ 19.5, 26.5 years], p = 0.03; senile retinopathy: 27.0 years [IQR 26.0, 30 years] vs. 24.0 years [IQR 20.0, 27.0], p = 0.04). None of the pathologies investigated were more prone to affect one versus both eyes (p > 0.05; 71.4% of ocular pathologies were bilateral while 28.6% were unilateral).

Main limitations: Data were obtained from a relatively small sample size of a single cohort of animals that lacked a control group.

Conclusions: There was a high prevalence and wide range of ocular lesions in this subset of geriatric equids.