Age-related visual decline in companion dogs: a cross-sectional ERG study in a translational model species.

Abstract

Purpose : Aging is an important risk factor for visual decline and retinal disorders such as human age-related macular degeneration. Companion dogs share many aspects of the human lifestyle and environment and develop other age-related ocular disorders such as cataract and vitreous degeneration. We hypothesized that age is negatively associated with retinal function in dogs, as measured by dark- and light-adapted electroretinography.

Methods : Participants included adult companion (pet) dogs with no significant ophthalmic abnormalities. All participants underwent unilateral dark- and light-adapted electroretinography following mydriasis (RetEval, LKC Technologies). We performed statistical analysis using R version 4.0.0 to calculate correlation, R squared, and coefficients of correlation between age and ERG parameters. We calculated the strength of association between ERG measurements and age, or age adjusted for expected lifespan of the breed for purebred dogs.

Results : Median age was 11.3 years for all dogs (n = 29, 21 purebred dogs from 11 breeds, range 6.1-15.4 years). Median percentage of maximum purebred breed lifespan was 62%. (n = 20, range 41-104%). Overall, age was associated to a greater extent with ERG amplitude (P value range 0.004-0.44) than peak time (P value range from 0.13-0.97). Age was significantly associated with the dark-adapted bright-flash a-wave amplitude (R² .27, P = 0.004) and b-wave amplitude (R² .15, P = 0.04); b/a wave ratio was not significantly associated with age (P = 0.32). Age was also significantly associated with light-adapted 33Hz flicker amplitude (R² .25 P = 0.006). When age was represented as a proportion of maximum breed lifespan, age was also significantly associated with light-adapted flash b-wave amplitude (R² .09, P = 0.012).

Conclusions : Aging in companion dogs is associated with a decline in both rod- and cone-mediated ERG amplitudes. Further studies are warranted to define the relationship between age-related decline in retinal function and vision and/or retinal structure. Companion dogs could be considered a translational model for human age-related vision impairment.

This is a 2021 ARVO Annual Meeting abstract.