PRA is a health condition that can affect a dog’s eyes. There are a number of different forms of PRA and there are many DNA tests that can check if your dog is clear, a carrier or affected. Find out more about PRA, including what it is, signs to watch out for, how to test your dog and how to help your dog if they're affected by it.
What is PRA?
Progressive retinal atrophy (PRA) is an umbrella term that describes a type of eye disease that affects the retina (the light-sensitive part of the eye), causing it to gradually shrink over time. The retina sits at the back of the eye and is built up of specialised cells called photoreceptors, which are able to absorb light that has passed through the lens. Electrical messages are sent to the brain, which translates these into an image. With PRA, the photoreceptor cells (rod and cone cells) within the retina slowly break down over time, causing vision problems and sometimes blindness.There are several forms of PRA:
- Generalised PRA - This is the most common form of PRA, affecting the whole of the retina.
- Retinal pigment epithelial dystrophy - This form of PRA, also known as centralised PRA or RPED, affects the outermost layer of the retina
- Sudden acquired retinal degeneration syndrome - This type, also known as SARDs, has a sudden onset and causes irreversible blindness
A number of different genetic mutations that cause each of these diseases have been found.
What causes PRA?
PRA is a genetic condition that is caused by a faulty genetic mutation within a dog’s DNA. The disease is most often inherited as a simple autosomal-recessive condition. This means that a dog must inherit two copies of an abnormal gene (one from its mother and one from its father) before its health is affected. However, some breeds, such as Samoyeds, may have a different type of PRA that is inherited in a different way - make sure to check your breeds A-Z page for further details on your breed’s type of PRA and how it is inherited.
What are the symptoms of PRA in dogs?
As a general rule, PRA gradually impacts a dog’s vision, slowly getting worse with time. The most common symptoms include:
- Bumping into things
- Getting confused or disoriented
- Loss of night vision
- Reluctance to go into darker rooms
- Dilated pupils
- Complete blindness
There is another form of PRA, known as SARDs or sudden acquired retinal degeneration, which, as the name suggests, comes on suddenly, and may cause dogs to have sudden blindness that comes on in a matter of days or weeks.
The signs of PRA are very similar to a number of other eye conditions, so if your dog is having problems with their vision, it’s worth taking your dog to the vet to get them checked out. By seeing a vet, it allows you to rule out any other problems.
At what age does PRA develop in dogs?
The age of onset varies depending on the type of PRA and your dog’s breed, with some dogs showing symptoms at an earlier age, and others only becoming affected later on in life. It’s worth looking at your breed’s A-Z page to learn more about any specific types of PRA in your breed.
How is PRA diagnosed?
If you suspect your dog may have any of the symptoms mentioned above, take your dog to either your local vet, or a BVA/KC/ISDS Eye Scheme eye panellist, for further investigation. Your vet will give your dog a general assessment to see how quickly their eye responds to light, and whether there are any changes in the retina, possibly suggesting PRA.
In more severely affected dogs, there may be several changes that can be seen with an ophthalmoscope examination.
A veterinary eye panellist will be able to confirm the above using more sophisticated tools, such as an electroretinogram (ERG), and rule out other causes of vision loss. An ERG can be sensitive enough to diagnose some forms of PRA before dogs begin to show obvious symptoms.
How common is PRA in dogs, and what breeds can be affected?
Many of the mutations known to cause PRA are thought to be ‘ancestral’, which means that they came about quite early on when breeds were being developed, and have spread across many different breeds of dogs. It’s worth checking your breed’s A-Z page to see if there is a testable form of PRA in your breed, however, some commonly affected breeds are listed below.
Commonly affected breeds
How do I test for PRA in my dog?
All dogs tested under the BVA/KC/ISDS Eye Scheme can be screened for PRA by a specialist veterinarian. We recommend that breeds known to have a hereditary form of PRA are routinely tested, particularly in dogs that are used for breeding. These dogs should be tested within 12 months before they are bred, to give an up-to-date picture of your dog’s health before you choose to breed from them.
Find out more about the eye scheme and how to find an ophthalmologist.
Some of the genetic mutations known to cause PRA can be tested for using a simple DNA test that can be easily purchased from a number of laboratories. You can find which labs offer this test for your breed by checking your breed’s A-Z page. DNA testing is a handy way of screening your dog for one particular mutation, but it’s important to remember that there are many different forms of PRA. We therefore recommend using both DNA testing and routine eye testing, to keep you informed of any other forms of PRA, or other eye conditions, that could be affecting your dog.
How much does it cost to test for PRA?
The cost of testing varies depending on the type of test you use, and where you get this from. If you decide to get your dog physically screened under the BVA/KC/ISDS Eye Scheme, you can find further information about how to book an appointment and idea of cost here. If you’re thinking of getting a DNA test for your dog, you may be able to buy a simple test for your dog from The Kennel Club, as part of our DNA Testing Services.
What does it mean if my dog is PRA clear?
If your dog carries no copies of the PRA mutation, they will not go on to develop that form of PRA. However, as mentioned above, there are many different mutations for PRA, and not all of these have been developed into a DNA test. Therefore, even if your dog tests clear for a form of PRA, we still recommend that you routinely screen your dog’s eyes with a BVA/KC/ISDS Eye Scheme assessment, particularly if you are planning on breeding from your dog.
Find out more about what your dog's DNA test results mean.
What does it mean if my dog is a PRA carrier?
A carrier has one copy of the abnormal gene that’s been tested for (either inherited from their mother or their father) but is unlikely to develop this type of PRA. If this dog breeds, it could pass on either the ‘normal’ copy of the gene or the abnormal copy of the gene to its offspring. This only applies to forms of PRA that are inherited in an autosomal recessive manner. You should check that your breed’s form of PRA is inherited in this way (you can do this via our Breeds A-Z).
Find out more about what your dog's DNA test results mean.
How can I help my dog if they are affected by PRA?
PRA is not a painful condition, but it can cause your dog to feel some confusion and uneasiness about their environment. There are several things you could do to them feel more at home, such as:
- Try to keep your furniture layout in place. Avoid moving lots of things in one go, otherwise it may make it difficult for your dog to navigate their way around
- Check your house at your dog’s level, are there are any sharp corners or potential hazards they might bump into? Baby gates can help stop them going up or down any stairs unattended
- Try to keep to a routine, particularly with feeding, walking and any play, so that your dog knows when to expect what
- Take walks a little slower, and try to keep to walks that have flatter ground so your dog is less likely to trip or stumble. You may find they feel more secure being kept on a lead
- You may wish to buy some leads, coats, harnesses etc, that alert other dog walkers that your dog is blind, and that people need to take extra care around them
- Update your dog’s microchip details to note that they are blind
- Try to teach your dog new commands to help them navigate their surroundings, such as “stop”, “step up”, “step down”
- Make sure you talk to your dog, particularly when approaching them, so that they are not startled.
It’s important to remember that dogs still have very strong senses of smell and hearing, and still need plenty of stimulation to keep them from getting bored. Scent games are a great way to keep them entertained and can be done both at home and out and about. Many dogs adapt perfectly well to loss of sight, but you will know your dog best and how they will be affected.
Where can I find further support and resources?
Your vet is the best initial point of call for further support on this condition and your dog’s individual journey for living with PRA.
You may also find it useful to seek advice from owners who have had similar experiences; we would recommend contacting your breed club or Breed Health Co-ordinator, as they may be able to share their knowledge with you and put you in touch with other owners who have had dogs affected by this condition. You can find out how to contact your Breed Health Co-ordinator at the bottom of the health section of your breeds entry on our Breeds A-Z.
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Think your dog may be affected?
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We are not a veterinary organisation and so we can't give veterinary advice, but if you're worried about any of the issues raised in this article, please contact your local vet practice for further information