Iris Cyst in Dogs


Reading Time: 7 minutes

As dog lovers, we want our furry pals to share our worlds with us. We bring them on trips, we take them for walks, we show them all the things and places that we love the most. And while we know that dogs rely more on smell and sound to understand the world, there’s still something about knowing that your dog is seeing the world through those adorable puppy dog eyes that makes us happy.

But what happens when your dog’s eyes aren’t in great heath? There are many things that can interfere with a dog’s vision, and one of those is an iris cyst. Also called uveal cysts, iris cysts can range from not problematic at all, to very worrying. In this guide, we’ll explain what an iris cyst is, and then go in-depth with everything you need to know about them, including:

  • Causes of iris cysts
  • Symptoms of iris cysts
  • Diagnosis of iris cysts
  • Treatment of iris cysts
  • Preventing iris cysts

If your dog has been diagnosed with an iris cyst, you’ll learn what you need to know to get started with treatments and management.

What Is an Iris Cyst?

An iris cyst is a hollow structure of cells that are filled with fluid, that is found in the eye. In dogs, it is most commonly simply floating around in the eye; however, it can also be attached to the iris of the eye. Iris cysts are also seen in cats and horses, but in dogs, it is most common to see them in Golden Retrievers, Boston Terriers, and Labradors.

To your eye, an iris cyst in your dog will look like a dark bubble or splotch in their eye. It may look like it is attached to a specific part of their eye, like the side of the iris, or it could look like it’s just hanging out in there. It could show up seemingly overnight. It can be very small, pretty large, and come in a variety of shapes and colors. It will most likely be accompanied by a dark film over the corner of the eye.

The iris cyst is not the same thing as a cancerous tumor in the eye, like melanoma. These are tumors, or growths, of cancer cells. Iris cysts, on the other hand, are hollow structures – think of something like an air bubble. They can be collapsed, or destroyed by a laser, and aren’t in and of themselves dangerous for a dog. In fact, if an iris cyst presents with no other symptoms or complications, it won’t be harmful for the dog at all.

In the vast majority of cases, an iris cyst does not impact a dog in any negative way – it’s simply a quirky feature that they have in their eye.

Causes of Iris Cysts

A dog can be born with an iris cyst, they can develop the cyst after some kind of trauma to the eye, or the cyst can simply appear. We don’t really know why this can happen.

We do know that iris cysts that are caused by trauma are usually related to other eye conditions, such as glaucoma. In most cases, however, the exact reason that your dog developed an iris cyst is unknown. Chalk this one up to a strange quirk of nature that cannot be explained. We don’t know why they occur, why they aren’t harmful, or why a dog can live their whole life with one without having any vision impairment.

Symptoms of Iris Cysts

As we said above, most iris cysts don’t cause any issues in dogs. In fact, they aren’t really that big of a concern if you see one appear in your dog’s eye, unless they start exhibiting other symptoms. And even then, it’s more likely that the cyst itself is also a symptom of a larger issue like glaucoma. Other symptoms that could be seen in conjunction with an iris cyst include:

  • The dog appears to be having trouble seeing. They may walk into walls, spend more time with their nose to the ground when navigating, or not look directly at you when you are talking. If the iris cyst is very large, or if there are many cysts in one eye, it could start to impair vision.
  • The eye may have trouble draining.
  • The dog’s behavior may change. They may act more cautious or more unwilling to engage with people and other animals.
  • The eye may be inflamed.

Vets don’t tend to worry about iris cysts unless there is a change in a dog’s vision or behavior. However, if the dog is a breed that is prone to things like glaucoma, which includes Great Danes, Bulldogs, and Golden Retrievers, the development of a cyst may be something to pay attention to, simply because it can indicate that glaucoma is looming or already developed.

Related Content:

Demodicosis in Dogs (Video)
Brucellosis in Dogs (Video)
Keratoconjunctivitis Sicca in Dogs (Video)

Diagnosis of Iris Cysts

The first thing that many owners want to know is how the vet can tell the difference between an iris cyst and melanoma. So, the first thing a vet typically does is shine a light at the dog’s eye. If the light passes through the cyst, it is indeed a hollow iris cyst. Melanomas absorb the light. If this test doesn’t give an exact result, an ultrasound may be performed to ensure that this is simply a fluid-filled iris cyst, rather than a solid mass of cancerous cells.

There are quite a few other tests that may be performed to fully diagnose an iris cyst. Your vet may perform a Schirmer Tear Test (STT), which measures tear production. If the eye isn’t producing enough tears, it could be a sign that there is a cyst.

Another thing the vet may do is use a fluorescein stain to find areas of abnormality in the eye. This stain gathers where there are unhealthy areas in the cornea, and can easily show if there is an ulcer or cyst in the eye at all.

The vet may also dilate the eye so that they can see the size and location of the cyst, or identify if there are any other cysts in the eye. It’s not uncommon to see more than one small iris cyst in one eye. This may look like a row of tiny bubbles in your dog’s eye.

Finally, a tonometry can be done, which measures the pressure inside the eye. This test usually tells the vet if the dog has glaucoma, but can also be used as a way to eliminate glaucoma. This test is part of diagnosing anything that could be causing an iris cyst.

Iris Cyst in Dogs

Treatment of Iris Cysts

In most cases, when an iris cyst isn’t changing the way a dog behaves or sees, no treatment is required or recommended. It’s better to leave something alone that isn’t hurting the dog, and consider it just another feature of your dog’s face – just like that pink freckle above their nostrils, or the spot of darker hair around their ear.

But if the cyst is causing your dog vision problems, there are a few treatments available. The first is surgical aspiration, in which the vet essentially “pops” or deflates the iris cyst. Another method is to surgically remove the cyst. Finally, a vet may use a laser to remove larger cysts through a process called coagulation. These procedures are generally performed by a special veterinarian who specializes in eye care, because these procedures require a lot of experience to do without damaging the eye.

One thing to note is that many times, benign iris cysts will simply rupture on their own in the future. This isn’t painful for your dog, and while it may lead to a bit of discharge from the eye, it doesn’t cause any sort of bleeding or issues with the eye itself. In fact, you may not even notice it has happened. One day your dog may just wake up without the cyst they’ve had since birth. Much like we don’t know what causes iris cysts to pop up, we also don’t know what causes them to eventually rupture and disappear.

Recovering from Iris Cyst Treatment

Recovering from these surgeries is straightforward. Bed rest and preventing your dog from bothering their eye while it heals are the two biggest concerns. He’ll likely have a pirate patch covering his eye until it is healed so that he doesn’t injure it future. Additionally, your dog will likely be sent home with eye drops or an eye ointment, as well as other medications like antibiotics and pain medication.

The prognosis for an iris cyst is very good. When performed by an experienced specialist, these surgeries typically take care of an iris cyst perfectly. And unless there is an issue, the iris cyst is so often just left alone that the prognosis is even better than very good for most dogs.

Preventing Iris Cysts

There is no way to prevent an iris cyst because we don’t know what causes them. Keeping your dog healthy, ensuring that they don’t get any injuries to the eye, and paying attention to their eyesight if they are a breed prone to glaucoma, is all you can really do.

It is important to note that while an iris cyst may not be treated if it is harmless, the underlying cause will be treated if the cyst was related to something more serious. The presence of the cyst may be the thing that lets the vet find out that your dog has something more serious. In this case, the eye condition itself will be treated, and the iris cyst may be treated at the same time.

Glaucoma treatment usually involves a lifetime management program of eye drops and pills. Glaucoma cannot be cured, but it can be lessened through laser surgery and other surgical options. If a dog has glaucoma, they’ll need regular eye examinations to ensure that they don’t have progressive vision loss. In this case, if a dog has surgery for glaucoma, it’s pretty likely that the iris cyst would also be removed or aspirated at that time.

The Final Word

To sum up what we learned in this guide:

  • An iris cyst is a hollow structure in the eye that may or may not be dangerous.
  • In most cases, iris cysts are not dangerous at all, and aren’t even treated.
  • If your dog starts to act differently, or appears to be having trouble seeing, you should get the iris cyst checked out. Surgery to remove or aspirate the cyst may be necessary.
  • An iris cyst may be a symptom itself of something more serious like glaucoma.
  • Most dogs recover 100% from iris cyst treatment, if it is even necessary at all.

So, the bottom line is, unless your dog is suffering from vision changes, there’s really no reason to worry too much about iris cysts. Be sure your vet is aware of the cyst so that they can eliminate any other worries, but if your dog is acting just fine, and can see as normal, then this cyst is no big deal.It may go away on its own one day, or your dog may always have this little feature.

What Should You Do?

If you own a dog that is one of the breeds prone to eye issues, keep a lookout for anything unusual in their behavior or their vision. Make sure you check your dog’s eyes during grooming sessions for changes in appearance. And if you see anything out of the ordinary, or if they start to act strangely, head to the vet to have an eye exam done. But don’t lose too much sleep over an iris cyst. These are common occurrences that don’t usually mean anything serious at all.

However, it’s still important to have your vet check a cyst out, if only to eliminate the possibility that your dog developed glaucoma. So, be sure to schedule that appointment if you notice strange “bubbles” or cysts in your dog’s eye.

Related Content:

Demodicosis in Dogs (Video)
Brucellosis in Dogs (Video)
Keratoconjunctivitis Sicca in Dogs (Video)