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My dog's eye is dilated after corneal ulcer treatment. Is this normal?

Updated on September 23rd, 2025

Pet's info: Dog | Dachshund miniature | Male | neutered | 12 lbs

My dachshund recently was at the vet for a corneal ulcer. it was a pinprick, not bad at all. it has been 3 days since hes been to the vet an his pain eye drops have been administered daily in the morning and the ointment the vet prescribed is being used regularly. today i noticed that the eye that was the issue is extremely dilated, so much so, that i cannot see the color in his eye. his other eye is fine. is this a problem?

3 Answers

Most Helpful Answer

Vanessa Yeager DVM MPH

Answered By Vanessa Yeager DVM MPH

Veterinarian

Published on December 3rd, 2017

Hi there and thanks for posting.

Yes, what Susan is experiencing is called Anisocoria; one pupil is larger than the other. Sometimes this can occur due to an injury to the cornea (she currently has), injury to the nerves of the eyes, or brain injury. It can also be caused by glaucoma of the eye, or severe inflammation of the interior portion of the eye. I would recommend Susan see her veterinarian again vet very soon to check for any other underlying conditions besides the corneal ulcer that may have caused or contributed to the anisocoria. Treatment is then based on the underlying cause.

I hope this helps and thanks for using Petco Pet Education Center, formerly Petcoach!
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Related Answers from Veterinarians

  • Answered By Destini R. Holloway, DVM

    Veterinarian

    Typically topical pain medication for the eye (ie Atropine) causes dilation. This is a normal effect of the eye medicine. However it is still important to express any concerns with the vet who prescribed your pets medication, just to make sure there aren’t other factors that we are not aware of. Otherwise there doesn’t appear to be an immediate concern and you should be able to discuss things with your vet first thing Monday morning. Best of luck to you and take care.

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    1Pet Parents found this answer helpful

  • Answered By Dr. Macartney, BVet Med, MRCVS

    Veterinarian

    Published on August 11th, 2017

    I am very sorry this is happening to Bella. The good news is her ulcer was treated early and healing well now. That is fantastic news. I have not seen a Phil stay dilated past the 48 hour window, however, it seems possible that Bella is particularly sensitive to the medication she received. This will be noted in her file and she will have a different medication if this occurs again or a reduced dosage. Your regular vet will have access to the medical notes from the ER,
    vet and will know the medication.

    In the meantime, protect the inner structures of her eye by keeping her in dark inside environment while the pupil is still dilated.

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    1Pet Parents found this answer helpful

Smart Picks for Smart Questions

Vet Q & A
My dog has one dilated pupil after neutering. Is it an emergency?
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.
Updated on September 23rd, 2025
Vet Q & A
My puppy's eye is cloudy and one pupil dilated after injury. What now?
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.
Updated on September 23rd, 2025
New Pet
My puppy has one dilated eye, but she's acting normal. Should I worry?
This can be a sign of an eye problem - the eye can dilate if a toxin has been ingested, or it's possible that the other pupil is actually constricted secondary to pain or a scratch on the eye. I'd recommend seeing your veterinarian for an exam of the eyes. If Nova seems to be painful or disoriented I"d recommend seeing an emergency veterinarian today.
Updated on September 23rd, 2025
Vet Q & A
Why is my dog's eye gray/blue, squinting, and pupil so small?
When this happens to one pupil it is known as aniscoria. The pupils should always be the same size. There are many reasons it can occur but considering you say you saw a blueness in the eye previously, I would be suspicious of a type of inflammation called uveitis. You will have to head to the vet to get Abbie an eye exam to determine exactly what is going on and get her the appropriate treatment. If it is uveitis it is usually treated with eye drops.
Updated on September 23rd, 2025
New Pet
My puppy's eye is blue and red. How to tell if her ulcer is healing?
You won't know how it is healing just by looking. We used lights, special stain, and small magnifiers to get a really good look at the eye. Blue appearance means that the cornea is swollen. Red in the white part of the eye is inflammation, which is normal. Red in other parts of the eye may not be normal. Definitely keep your appointment on Saturday. Also, if they didn't give you one, I recommend wearing an e-collar, since dogs often will rub their eyes when there is discomfort, and this rubbing can delay healing.
Updated on September 23rd, 2025
Vet Q & A
My dog has low eye pressure after a corneal ulcer. Is this normal?
Yes this is totally normal! It can have a mild uveitis (low pressures) after an ulcer while it is still healing. Have your vet recheck the stain and the pressures at your recheck. I hope this helps!
Updated on September 23rd, 2025
Vet Q & A
Why is my dog's one eye not dilating to light? What should I do?
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.
Updated on September 23rd, 2025

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