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Why are my dog’s eyes swollen?

My dog Ace is being treated for polymyositis, also called extraocular myositis. He is the black dog in the photos. The condition is caused by an allergic reaction where the dog’s extraocular muscles in the back of the eyes swell.

As a result of the swelling, the whites of the eyes bulge and make the dog look really goofy as you can see in the bottom photo of the golden retriever, submitted by a reader.

I wrote about my dog’s swollen eyes a few months ago. I’ve gotten a surprising amount of search engine traffic from people desperately looking for a reason why their dog’s eyes would be swollen.

I was in the same position. With polymyositis, the eyes can flare up so quickly it’s scary.

When I first noticed Ace’s swollen eyes, I knew nothing about polymyositis – either did his regular veterinarian or the on-call person at our local emergency vet clinic.

The good news is polymyositis is not life threatening. I spoke with a canine eye specialist who reassured me that although this condition would take awhile to treat, Ace would recover just fine. It doesn’t really affect the dog much except when it’s at its worst.

Before I treated Ace, his eyes were so swollen he had a hard time seeing. He was depending on one eye because it was too difficult for him to see straight when his eyes were bulging out in opposite directions.

Black lab mix with swollen eyes, called polymyositis or extraocular myositis

When my dog’s eyes were totally bulged, I didn’t take any pictures. I was too worried about my dog at the time. At its worst, the whites of both eyes were swollen all the way around and under the eyelids.

All the research I’ve come across says young retrieving breeds are the most likely to develop polymyositis, which could be a reaction to anything – grass, carpet material, dust, wheat – who knows.

It’s most common in female golden retrievers under 3 years old. Vets can do an allergy test to determine possible allergens once the dog is off medication.

The specialist I’ve worked with said to go with a skin test because it is the most reliable and effective. A blood test can’t detect the same information.

For anyone who has a dog with swollen eyes, take your dog to a vet. You won’t find the answers you need by searching Google.

I can give you answers only based on what I’ve learned, but I am not a vet. And if your vet has not heard of polymyositis or extraocular myositis (mine had not), then find a canine eye specialist who can give you the answers you need.

Black lab mix with swollen eyes, called polymyositis or extraocular myositis

My dog has polymyositis

Here is my experience with polymyositis with my 65-pound, 2-year-old black lab mix:

Ace was diagnosed with polymyositis around October 1, 2008. He was on a heavy dose of Prednisone (80 mg daily), which decreased the swelling in his eyes dramatically after about 11 days.

Two weeks later I decreased the dose by half as told, but his eyes swelled again. I repeated the process, returning to the heavy dose. His eyes went back to normal, so after another two weeks I decreased the dose again. Like the first time, his eyes swelled again.

Next, Ace was on the heavy dose (80 mg daily) for a month straight. He is now in the process of slowly being weaned off the Prednisone.

By slowly, I mean slowly. Just to make sure his eyes won’t flare up again, I am cutting his daily dose in half each month over a six-month period. His eyes are not fully back to normal, but hopefully they will continue to improve with the Prednisone.

The chances of the polymyositis reoccurring are much less likely the longer he stays on the Pred. Luckily, Prednisone is not an expensive drug, even without pet insurance.

Golden retriever with swollen eyes due to polymyositis or extraocular myositis

Polymyositis often reoccurs two or three times per dog over several years, but the specialist I worked with said she has never seen it reoccur more than three times. The longer a dog is on Prednisone, the less likely it is for the myositis to come back.

In all cases, dogs must be weaned off Pred slowly. Prednisone is a steroid, so when a dog is on a high does, his body stops producing the natural steroid hormone called cortisone.

If a dog is suddenly taken off Pred, his body won’t have enough cortisone, and he will be vulnerable to infections. In extreme cases, he could go into shock or a coma.

Some of the side effects to Prednisone are nasty. My dog is a totally different dog on the drug. But the benefits of the drug are worth it in Ace’s case. Now that he’s on a lesser dose, the side effects have started to decrease already. Here are some side effects I noticed:

My dog was always hungry

This dog was ravenous. Ace is normally not food crazy. Before Prednisone, he would skip meals if he wasn’t hungry. On Prednisone, he ate his food in seconds even though I increased his meals by a cup or two a day.

He stole from the counters and begged like he’d never eaten in his life. My dog ate from the litter box, raided the garbage, tried to eat all the snow in our yard and ate the pockets from my jeans and coat (where I’d kept some treats).

My dog was always thirsty.

My dog has always been obsessed with water. But add the drug and he’s even worse. I had to ration his water because he would literally never stop drinking.

This dog was finding water in all sorts of places and drinking it – entire toilet bowls, tipping over our water glasses, licking the snow off my shoes, etc.

My dog had to pee all the time.

Yup, as in every hour. And this dog had to go a lot!

My dog was always tired.

Some dogs actually get more energy on Pred. Ace was very mellow. He heeled better, chilled out a little during agility and was more content to just lie around the house. It was actually kinda nice.

My dog became more vulnerable to infections.

Because of the way Pred works with the body’s immune system, Ace developed an infection on his stomach that probably started as something as tiny as a scratch.

The Prednisone suppresses a dog’s immune system. This infection required another trip to the vet and antibiotics.

Make sure your vet knows your dog is on the drug before she gives him live vaccinations because your dog’s immune system will not be functioning normally.

My dog experienced muscle atrophy – a decrease in his muscle mass.

I first noticed Ace’s muscle mass decreasing in his back. His spine stuck out even though he was eating more and exercising less. His stomach and chest were bloated from water retention.

And then his bones started to show in his head and face as he started developing “Pred head” where the muscle around his head also decrease.

Dogs with Pred head have an odd shaped head with the sides sunken in and the bone sticking out on top. Ace’s head was starting to look almost triangular. It was awful because I know people were thinking, “All she does is run that dog and not feed him enough.”

My dog was always starving and he looked so thin. The good thing is the dog’s body returns to normal once he’s off Pred, and Ace has already started to improve.

Should I give my dog Imuron (Azathioprine)?

For some dogs, Prednisone does not take care of the polymyositis. One option is to give them a drug called Imuron (also called Azathioprine). This drug is more powerful than Pred, so make sure you understand the side effects before giving it to your dog.

I decided even though Ace’s eyes are not perfect, I would rather continue with the Pred and not go with Imuran.

The side effects of Imuran are not worth it in his case. If his condition were life threatening or if he were an older dog, it might be different. But he doesn’t even know his eyes are swollen and he is a 2-year-old dog with several years ahead.

Some potential side effects of Imuran include high risk of infections, nausea, vomiting, hair loss and an increased risk of developing cancerous growths.

If your dog has swollen eyes, make sure to take him to a vet and get a professional’s opinion. I

f you think your dog has polymyositis, feel free to send me a picture, and I can tell you right away if that’s how my dog’s eyes looked. I can answer any questions based on what I’ve gone through with Ace, but for treatment and diagnosis, consult with a canine eye specialist.

Also, see my previous post on my dog’s swollen eyes.

Kandi Speiser

Tuesday 14th of March 2023

I want to thank you so very much for this article!!! My dog’s eyes were swollen, quite rapidly swollen, approximately a week ago. We were send home with eye drops and benedryl. Both helped some but she continues to look bug eyed. I began to be very concerned for her (though she truly has no other symptoms). I found your article and know, no doubt that my pup (a 10 month old female golden Retreiver) has the same issue. We will be seeing her vet tomorrow and I will be mentioning extraoribital myosistitis and requesting prednisone for treatment. Thank you again for sharing!!!


Sunday 26th of December 2021

Good morning: My 3 year old Shih Tzu has the corner white part of her left eye swollen. I will take her to the vet but being Sunday, during the holidays and with Omnicron spreading around it's being difficult to find a vet that will take her promptly. Would like to send you a picture so you can tell me what you think. Thanks

Lindsay Stordahl

Sunday 26th of December 2021

You can send to

I'm not a vet but can let you know if she looks like she has what my dog had.


Sunday 26th of December 2021

Thank you for writing this article! Unfortunately our 6 month old female golden retriever likely has this condition. We started noticing her eyes looked glassy and bigger than normal, and then by the next day we took her to the vet because her eyes were bugging out and looking in different directions. I found this article before going to the vet and asked if it had anything to do with an allergic reaction, but she did not think so and said it was likely an autoimmune disease or cancer. The vet prescribed her 20mg of Pred, which does not seem like a lot compared to the other comments. She weighs 43 pounds. After the first couple of doses it actually seemed like it was going down, but a couple days after that it seemed like it got worse. Tomorrow is day 5 so hopefully we start to see some results soon, but the side affects have not been fun. She already had a big appetite and had to pee every hour, but now she can’t go s’more than 2 hours at night without having an accident. This post gives so much hope that eventually this will be behind us. Our girl has no other symptoms besides the bulging eyes.


Sunday 25th of July 2021


Thanks for the info in your article!! I have a one year old golden retriever that has been diagnosed with extra ocular myositis which I’m pretty sure is another name for what your dog Ace had. She was started on 50 mg of prednisone for 4 weeks then decreased to 3/4 of a pill for 3 weeks. Now that we have dropped to half (25mg) her eyes have started to bug out again. I’m hoping as she normalizes to the dose the bulging subsides. So frustrating lol. Nice to know we are not totally alone in the very rare disorder.

Did Ace ever have a relapse?

Thanks again!

Lindsay Stordahl

Sunday 25th of July 2021

Ace's eyes bulged as I decreased the pred too the first time. So we gave a higher dose and then decreased slower. That worked. He never had the issue again.


Friday 23rd of July 2021

I'm so happy that I have come across your article. We just started the prednisone today to treat our dog for polymyositis (3rd time). She is only 18 months old. Since your article is a little older, have you experienced anything new? Have you found a new drug that might not be as hard on the dog? Any advice would be greatly appreciated.

Lindsay Stordahl

Friday 23rd of July 2021

The prednisone worked and my dog did not have any issues with his eyes after that. He did have a lot of other allergies throughout his life such as itchy skin and ear infections but never the swollen eyes again. Unfortunately I don't know of another drug that would help.