Progressive Retinal Atrophy

A dog with decreased vision may be reluctant to go down stairs or go into a dark room or outside at night. They may bump into door frames or corners and have difficulty fetching toys. You may notice a characteristic eyeshine due to increased reflectivity of the tapetum, the layer of the eye that reflects light. The dog's discernible visual impairment will typically lag behind changes observed by a veterinarian and electroretinogram (ERG) abnormalities.

Changes may be observed as early as 2 years of age, leading PRA to be “suspected.” The average age of the PRA “affected” diagnosis is 9 years, but varies. The disease progresses slowly, as some affected dogs may still have some eyesight left at 13 years of age.

PRA is diagnosed by examination of the back of the eye (the "fundus"). In the early stages, it may be difficult to observe changes to the retina, but as the disease progresses, a veterinarian will notice increased reflectivity, thinning of the retinal blood vessels, and atrophy of the optic nerve. Changes affect both eyes equally, helping to distinguish PRA from other retinal diseases. A veterinary ophthalmologist can perform an ERG, which measures the electrical activity, and thus the function, of the retinas. An ERG is crucial to evaluate for PRA prior to considering cataract surgery.

Currently, there is no widespread treatment for progressive retinal atrophy. However, gene therapy is an evolving field.

Talk to your vet about your dog’s PRA result so you can work together to plan their ongoing care and monitoring.

Schedule regular eye exams with your vet or a veterinary ophthalmologist to monitor for changes or complications such as cataracts.

If your dog’s vision changes, help them adjust by keeping furniture and routines consistent, using verbal cues, and keeping them on a leash in unfamiliar areas.

Products such as protective halos can also help dogs navigate safely if their vision declines.

This variant was first identified in Lapponian Herder dogs.

Penetrance: PRA is inherited in an autosomal recessive manner, meaning that affected dogs must have two copies of the variant to show clinical signs from it.

Gene

IFT122 Exon 26

Inheritance type

recessive

Clinical category

Ophthalmologic

Citations

1. Kaukonen et al 2021
2. Mellersh 2014
3. Miyadera et al 2012

• Lapponian Herder