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Why is my dog's one eye not dilating to light? What should I do?

Updated On September 23rd, 2025

Our dog’s right eye doesn’t dilate/respond to light. We don’t know what caused it. Please help

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1 Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on May 5th, 2018

This could be caused by trauma to the eye, the nerves leading to the eye, or even the brain. It could also be caused by an infection. It's very concerning when there's a problem with the eye such as this, and it requires an immediate vet visit. That's because leaving it untreated can lead to permanent vision loss. Please take him into an ER vet clinic; if there isn't one in your area, there will be a vet on call for emergencies. The information to reach that vet is found on a clinic's answering machine or website. Best of luck.

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