Before starting her full-time writing business, Sarah worked with a top pet food company as a consultant to veterinarians conducting weekly classes on canine and feline nutrition for the doctors and staff.
Latest posts by Sarah Hansen (see all)
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For humans, the thought of going blind is terrifying. After all, vision is central to much of our interaction with the world.
We also would hate to see this horrible event happen to our furry friends.
Since dogs also have sharper hearing and smell than humans, they are actually able to adapt to blindness better than their owners. However, it’s still devastating to see them lose the ability to see.
Unfortunately, some Labrador Retrievers suffer from an insidious loss of sight that happens so slowly, it’s almost imperceptible. Since our fur kids can’t talk, it’s up to us to become educated on this disease that silently steals away their vision.
This visual disorder, called Progressive Retinal Atrophy (PRA), is what may be slowly robbing that spark from your dog’s eyes.
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What is Progressive Retinal Atrophy or PRA?
PRA is a general term for a combination of disorders that slowly affects the retinas of a dog’s eyes over time, eventually leading to blindness.
The retinal tissue, as the name suggests, eventually atrophies until the entire retina is dead and the dog is unable to see.
PRA affects the rods within a dog’s retina. If you remember from biology class, the retina, which is found at the back of the eye, is divided into rods and cones.
These rods and cones turn visual stimulation into electrical impulses that the brain reads as sight. Rods are responsible for night and black and white vision, and cones are responsible for color.
Contrary to popular belief, dogs actually can see some color, just not at the level of humans. Dogs eyes are about 95% rods with 5% cones, making their night vision much better than ours, but enabling us to see color much better than our canine companions.
PRA slowly attacks the rods of the eye, killing them and causing the retina to degenerate.
It’s usually found in dogs between one year and eight years old. However, it is also seen in puppies and older dogs. Unfortunately, the inevitable result is often total blindness for the dog.
What Dogs Get PRA?
PRA is found in many different types of dogs, but Labrador Retrievers are prone to this disorder identified in certain genetic markers associated with the breed. Other breeds plagued by the disease include collies, Irish setters, miniature poodles, cocker spaniels, Briards, mastiffs, Samoyeds and Siberian huskies.
Labs are more prone to a subset of PRA called central progressive retinal atrophy, which means they initially lose their central vision, but can often keep their peripheral vision for years before it finally fades away.
Genetics Components of PRA
Genetics are by far the most common cause for this disease. There is a marked faulty development in a group of cells in the retina, which worsens over time and eventually spreads to the rest of the rods.
However, with additional genetic research into mapping out the faulty genes, many breed-specific blood tests are now available to ensure dogs aren’t carriers.
If you are interviewing a breeder to get a puppy, it’s very important to know if they test for PRA prior to breeding their dogs.
Due to the fact that many dogs don’t develop PRA until later in life, after they have produced many litters of puppies carrying the faulty gene, it’s crucial to rely on genetic testing to make sure the parents aren’t carriers.
If your Labrador develops PRA, you need to inform your breeder immediately to ensure they change their breeding protocol. Additionally, all of the siblings of the dog with PRA should not be bred. Even if they don’t develop the disease themselves, they are carriers.
Other Causes of PRA
While genetic deformities in the eye are the main reason dogs develop this disease, there are additional causes for progressive blindness due to the retina slowly dying.
- Long-term glaucoma, scarring and inflammation of the retina, or separation of the retina due to trauma.
- Metabolic issues from insufficient or excessive amounts of enzymes.
- Cancer from other areas of the body that spreads to the retina.
- Nutritional deficiencies: specifically lack of Vitamin A or E.
- Retinal infections that spread from other parts of the body.
- Adverse reactions to specific drugs or toxins.
Sadly, in many cases, the exact cause of the PRA can’t be determined.
How Do You Know If Your Lab Has PRA?
Dogs are actually very good at hiding their blindness and sharpening their other senses to adapt. Because of the slow progression of PRA, dogs have ample time to learn to rely more on their hearing, smell, memory of their surroundings and touch.
PRA is usually painless, which means your dog just quietly learns how to get around in other ways as their visual world slowly fades away.
If you don’t frequently rearrange your furniture, your dog’s PRA may be fairly advanced before you notice any signs. There are usually no obvious outward signs around the eye such as squinting, redness or excessive tearing.
Usually, the first signs that your dog is developing PRA is night blindness, which then progresses to total blindness even in the day.
You may notice your dog is more reluctant to run the entire yard at night, and instead stays within the glow of the porch light. They may be afraid to go into a dark room, but will happily go into the room when you turn on the light.
As the disease continues to advance, you may start to see changes in the eyes. The dogs pupils may be dilated or have a slow response to light.
Some Labrador owners even report a characteristic shine to their pet’s eyes as the retinal tissue dies off to reveal the iridescent tissue underneath the retina known as the tapetum.
Some owners also notice the eyes becoming cloudy or opaque, although this doesn’t always happen.
How Is PRA Diagnosed?
The best way to catch PRA early is with routine eye examinations from a veterinarian. It’s often difficult for owners to notice the slow progression to blindness in their dogs, which makes eye check ups essential to catching it right away.
An ophthalmologist can view the retina with an instrument called an indirect ophthalmoscope. With this tool, they will be able to see changes in the blood flow to the retina, the optic nerve and the tapetum.
Another way to diagnose PRA is by electroretinography. This test measures the electrical impulses produced by the retina, similar to the way an ECG test measures the beat of the heart.
Electroretinography is widely regarded as the best way to determine a definitive diagnosis.
How To Prevent and Treat PRA
Unfortunately, the tough truth is that there isn’t much you can do to prevent or treat PRA.
Since there are some nutritional components to this disease, you need to make sure you are feeding your pup the highest quality food to give them everything they need for proper eye development.
Some vets promote certain antioxidant therapies to slow the progression of PRA, but as of yet there is no confirmed treatment or cure.
Some dogs do develop cataracts in the later stages of PRA. While you can perform surgery to remove the cataracts, as long as they aren’t causing any pain, it is often not necessary.
Even if the cataract is removed, the true cause of the blindness is in the damaged retina.
However, while blindness can often be traumatic for the owners, most dogs actually do just fine sharpening their other senses to still get around easily without additional stress.
Since this disease progresses slowly and is usually painless, the gradual loss of vision gives the dogs adequate time to learn to rely on their other senses and map out their surroundings.
PRA is actually more traumatic for the owners than the dogs, as they tend to try to put themselves in the dog’s position and relate to how they would feel if they went blind.
Since PRA is usually a painless condition, and dogs tend to live in the moment, it’s not as devastating for your Lab to slowly lose their sight.
While it may be tempting to humanize this condition, dogs have much better senses of hearing and smell than we do. Losing their vision is usually not a traumatic experience as long as their surroundings remain predictable and they are with their loved ones.
In fact, it’s better for the dog if you remain happy and calm during this time, as our pets are very perceptive to our moods. They need your guidance and love, not your pity and sadness.
With a bit of research, owners can learn how to help blind dogs transition into a world where they rely on their other senses to lead happy, healthy lives.
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