As puppies develop in the womb, one thing that happens is that the eye develops. The iris of a dog’s eye, or the colored ring, starts off as solid tissue, which is called the pupillary membrane. As the puppy develops more, the solid tissue dissolves, and then the pupil shows through. This is the normal state of a dog’s eye.
However, some puppies are born with part of that solid tissue still intact. In fact, it’s really not unusual at all to see this tissue for up to two months after a dog is born. But if the dog has that solid tissue after two months of age, it is considered a defect. In this guide to persistent pupillary membrane, we will cover everything you need to know about this condition, including:
- Causes of persistent pupillary membrane in dogs
- Types of persistent pupillary membrane in dogs
- Symptoms of persistent pupillary membrane in dogs
- Diagnosis of persistent pupillary membrane in dogs
- Treatment of persistent pupillary membrane in dogs
- Prevention of persistent pupillary membrane in dogs
This defect is very commonly seen in Chows, Basenjis, Yorkies, and Corgis, though it can occur in any breed. Here’s what you need to know about this condition.
Types and Causes of Persistent Pupillary Membrane in Dogs
There are four main types of persistent pupillary membrane in dogs. Each can cause different symptoms, and each is related to different causes. The four types of persistent pupillary membrane in dogs include:
- Free-floating: In this type of persistent pupillary membrane, the strands of solid tissue are attached to one end of the iris, and they “float” in the chamber of the eye. The impact of these types of strands can range from insignificant to serious.
- Iris to iris: This type of persistent pupillary membrane involves the strands of the tissue stretching over the pupil, being attached to both ends of the iris on either side of the pupil. These types of strands usually don’t have any negative impact on the dog.
- Iris to lens: This type of persistent pupillary membrane means that the strands of the tissue are attached to the iris, and then go through the pupil to attach to the lens of the eye which is located behind the iris. These types of strands can cause minor vision problems in the dog as well as cataracts.
- Iris to cornea: In this type of persistent pupillary membrane, the tissue attaches to the iris, and then to the back of the cornea, which is located in front of the iris. These types of strands are the most serious and can cause total blindness.
Ultimately, these are birth defects and are considered a hereditary condition. They are caused by a genetic defect, which is passed down from parents or grandparents. There is no other cause known for these conditions, but it’s important to note that the type of persistent pupillary membrane is caused by a different type of genetic defect. While this doesn’t change how we treat or prevent persistent pupillary membrane, it is good to know that you should look for the same type of persistent pupillary membrane if you breed a dog with the condition.
Many times, even most times, this condition will just clear itself up. Dogs that have this condition may wake up with clear eyes one day, and you’ll never see the strands of tissue again. In this case, the dog was just a little slow to develop the way other puppies do, and there is nothing to worry about.
Symptoms of Persistent Pupillary Membrane in Dogs
The only symptom of persistent pupillary membrane is that the dog may experience vision problems and that you’ll see the tissue strands in the eye. Signs that your puppy could be having problems with their vision include:
- Being far more clumsy than other members of the litter
- Being very easy to startle, or seeming apprehensive all the time
- Having trouble finding food, water, and toys without being directed to them
- Sleeping frequently, and not being as playful as the rest of the litter
- Seeming disoriented or confused
- Bumping into walls and furniture when walking
- Seeming uncomfortable in the dark
It can be hard to detect vision problems in a puppy because many of these behaviors can be chalked up to being a clumsy puppy. However, that is why breeders are encouraged strongly to do vision tests (as well as hearing tests and so on) on their litters. And if you’ve adopted a puppy and aren’t sure if these symptoms are problems with the vision or just a puppy learning, take a look at their eyes. If you see cloudy spots or anything that looks out of the ordinary in the eye or across the pupil, have your dog checked out by a vet. This is the best way to ensure that nothing is seriously wrong, and can also establish a baseline for future visits as the vet monitors the development of the persistent pupillary membrane in your dog.
Diagnosis of Persistent Pupillary Membrane in Dogs
In order to diagnose persistent pupillary membrane in your dog, the vet will perform a visual inspection of the eye. Usually, if something is suspected to be wrong, your vet will refer you to a veterinary ophthalmologist, or an eye specialist for dogs. This person has special experience and special tools that can help them check out the eye up close and make a final diagnosis.
The vet will want to know the medical history of the dog’s parents and grandparents if possible. If there is a history of persistent pupillary membrane in the line, that can determine the diagnosis. After diagnosing persistent pupillary membrane, the vet will determine what type of persistent pupillary membrane the dog has, checking for where the tissue strands are connected so that they can make an estimation of how serious the problem is. An “iris to lens” or “iris to cornea” type of persistent pupillary membrane are the most concerning, as they can cause cataracts and serious vision loss, respectively.
Treatment of Persistent Pupillary Membrane in Dogs
Unfortunately, there’s no way to treat this genetic disorder. Most of the time, persistent pupillary membrane resolves itself. Puppies may just be slow to develop, and the persistent pupillary membrane will dissolve the same way it did in the healthy puppies from the same litter. In some cases, the dog may always have that clouded appearance to their eyes, but it won’t ever impact their vision. However, if the type of persistent pupillary membrane that the dog has could cause damage, there are some things that a vet may be able to do to help prevent vision loss. These things won’t be cures by any means, but they may help your dog retain their sight.
For example, in the “iris to lens” type of persistent pupillary membrane, cataracts are often seen. The vet could surgically remove cataracts to help with retaining sight. As long as the cornea isn’t affected by the cataract, this could help return 100% of a dog’s vision.
However, there is no way of knowing if this will be a long-term solution for a dog that has hereditarypersistent pupillary membrane.
Prevention of Persistent Pupillary Membrane in Dogs
The only way to prevent persistent pupillary membrane in dogs, in general, is not to breed dogs that have persistent pupillary membrane in their history or their parents’ history. There is no way to prevent this problem from happening in the womb, so it’s up to breeders to be responsible about weeding this defect out of the population. If you own a breed that is prone to this condition, be sure that you know your dogs’ medical histories very thoroughly, and consider spaying or neutering any dog that has this issue. Only through that action will we be able to slowly get rid of this condition in most dogs.
Persistent Pupillary Membrane is Not a Death Sentence
Although the idea of your dog losing his vision is very serious and should be corrected if possible, having a blind dog isn’t a life or death situation. Your dog can still live a long and happy life even if their persistent pupillary membrane is very serious. Some of the ways that your daily life with a blind dog may change include:
- You’ll need to be sure to communicate audibly with your dog more than you think. Your voice is a soothing, stabilizing factor for a dog that can’t see, and it will help alert them to where you are and what is happening. They’ll use the tones of your voice in place of reading body language to understand the “mood” of the room.
- Consider putting bells on the collars of your other pets, so that your blind dog is never startled by their fellow pack members.
- You’ll need to keep their routine very similar so that they feel grounded and secure. Keep their walks and meal times as similar every day as possible. Be sure they always have their favorite toy, and consider buying backups so that they don’t have to get used to a new, unfamiliar thing if theirs goes missing.
- Noise and smell will be the two most important ways that you interact with your dog now. Choose toys that make noise, such as a squeaky toy or something with a bell.
- Keep indoor areas safe for your blind dog. Block off stairs, use carpet runners on slippery floors, and try not rearrange your furniture too often. Create a space in your home where you never change anything, and let this be your dog’s “base camp” that they can retreat to for familiar surroundings.
- Make sure you spend more time training your dog with specific commands. In addition to sit, stay, and so on, teach your dog to “stop” so you can stop them from walking into something, or teach them “left” and “right” so you can direct them in public places. These specific commands help keep them safe.
As you can see, living with persistent pupillary membrane and maintaining your dog’s healthy life is fairly simple – it just takes attention from you. The important thing to note is that if persistent pupillary membrane is serious, it won’t impact your dog’s overall lifespan or life quality with the right owner.
The Final Word
Persistent pupillary membrane is a condition in which a puppy’s eyes don’t develop correctly in the womb. Instead of the solid tissue of the iris dissolving into a ring around the pupil, some of the solid tissue will remain. This could cause problems with the puppy’s vision – or not. Some dogs live their whole lives with this condition and never have any problems.
For the most part, there is no treatment, unless the vet believes they can remove a cataract that was caused by the persistent pupillary membrane to help improve vision. Dogs that have vision problems due to persistent pupillary membrane may simply have to live with this issue. Luckily, living with a vision-impaired dog isn’t that hard. Many owners have long and happy lives with their dogs after they have vision issues.
The most important thing that we can do as humans to help stop persistent pupillary membrane is to stop breeding dogs with this condition in their medical history. This condition is genetic, not caused by anything else, so selective breeding could actually help weed it out of the population. Responsible breeders should spay and neuter dogs with persistent pupillary membrane, or dogs whose parents had persistent pupillary membrane, as it can be passed down to puppies from dogs that fall into these categories.
If you see your puppy struggling with getting around, or you notice cloudy lines or spots in your dog’s eye, take them to the vet to have their vision checked. While it could be a case of persistent pupillary membrane that won’t ever harm your dog’s vision, it’s better to keep an eye on it from the start.