My puppy has one dilated eye, but she's acting normal. Should I worry?

Yes, that is definitely something you should be worried about. What you are seeing is called anisocoria, and when it suddenly appears, it is a medical emergency. This can be due to corneal injury, disease or injury to the brain, disease or injury to the nerves running to the eye, or uveitis among other causes. I would take Ace into an ER vet or find a vet on call to see him ASAP to diagnose what is causing the anisocoria so it can be treated.

Poor pup! Cloudiness and anisocoria (the medical term for unequal pupils) are signs of a significant eye injury. It would be best to have Massimo examined by an emergency vet tonight if possible. If this isn't an option for you, he should be seen by your regular vet first thing in the morning. Prompt assessment and treatment is important in cases like this because the risk of permanent damage or vision loss increases the longer he goes without treatment.

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.

Hello and thank you for contacting Petco Pet Education Center, formerly Petcoach. Oso definitely should be fully checked by your local vet. Difference in pupils size can be caused by ocular trauma (for example blunt trauma to the eye when Oso hit the bench) or less frequently, by brain concussion / brain trauma. Your vet will be able to distinguish between these two problems and recommend treatment, if required.

Dilated pupils that don't constrict when exposed to light can be a sign of blindness or decreased vision and usually signifies a problem with the retina, optic nerve, or the brain. Pupils can also dilate from certain toxins. I would recommend having your vet examine Max's eyes if you're concerned.

This is a medical condition called [anisocoria](https://www.tuftsyourdog.com/doghealthandmedicine/dog-has-different-sized-pupils/) - most of the time, it indicates either a neurological problem or an injury to one of [the eyes](https://www.petcoach.co/article/sight-development-in-the-dog-puppy). However, occasionally in some puppies this condition may occur intermittently with no obvious cause and no other symptoms associated with it - the cause is as yet unknown, but the puppies are otherwise perfectly normal. If this is the first time you have noticed this, I would recommend taking Tucker to a veterinarian or [veterinary ophthalmologist ](https://www.acvo.org/)for an exam to be on the safe side - he may have an eye or head injury, some type of neurological disease, or been exposed to something toxic that could cause this. If his exam is completely normal and he shows no other symptoms, then in the future you could choose to simply monitor at home for other problems.

The pupil can constrict with bleeding or inflammation in the anterior chamber of the eye, blunt trauma, or a scratch to the surface of the eye. If you see blood, if your dog is squinting or seems painful, or if there is discharge from the eye I’d recommend traveling to see an emergency vet if at all possible since some conditions could compromise vision if left untreated. Otherwise I think you could monitor her for a day but if the pupil does not return to normal within 24 hours I’d recommend seeing a vet.