Progressive Retinal Atrophy in Dogs

Causes, Treatment, and Prevention

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Progressive retinal atrophy (PRA) is a hereditary disease that affects a dog's ability to see. There are two different forms of PRA that progress towards blindness. While not painful, PRA is life-changing for your dog and you should understand the condition to best prepare for the care of your pet.

What Is Progressive Retinal Atrophy?

Progressive retinal atrophy is the degeneration of the retina. It primarily affects the cells of the retina called rods and cones but can also affect the pigmented cell layer below the rods and cones. Rods allow a dog to see movement and in low light conditions, cones allow a dog to see in color, and the pigmented epithelium layer helps to protect and maintain these rods and cones. In PRA, these rods, cones, and/or the pigmented layer deteriorates and is eventually worn away causing blindness.

Two main forms of progressive retinal atrophy affect dogs and they are both considered to be hereditary:

  • Generalized progressive retinal atrophy (GPRA): The most common form of PRA, generalized progressive retinal atrophy, can occur in both young and old dogs. In early-onset GPRA, the rods and cones have not properly developed and therefore the dog has problems seeing. In late-onset GPRA, the vision loss is gradual since the rod and cone cells formed correctly but instead deteriorate over time. This form of PRA isn't usually noticed until at least three years of age when a dog with this hereditary condition starts exhibiting signs of vision impairment.
  • Central progressive retinal atrophy (CPRA): The less common form of PRA, central progressive retinal atrophy is also known as retinal pigment epithelial dystrophy (RPED). This rare type of eye disease causes the pigmented layer of the retina to deteriorate and therefore makes it difficult for a dog to see in low light. It is most often seen in older dogs and does not always cause complete blindness.

Symptoms of Progressive Retinal Atrophy in Dogs

The most obvious signs of progressive retinal atrophy are directly related to a dog's ability to see well. It can take months or years for the disease to fully take hold of your dog's eyesight. If you observe the following signs, call your vet.

Symptoms

  • Night blindness
  • Day blindness
  • Bumping into objects
  • Difficulty seeing in bright light
  • Unable to follow hand signals/commands

Night Blindness

Dogs can normally see in dark conditions. But nighttime and low or dimmed light situations may cause a dog with progressive retinal atrophy to have trouble seeing. You might be calling for your dog to come into the house at night while it is in the yard and it can't find its way back home. Getting lost in the dark is a regular occurrence in dogs with vision problems. A dog with signs of night blindness may also act very nervous to go outdoors in the dark or be in a room without light.

Daytime Blindness

Night blindness occurs first in dogs with progressive retinal atrophy. The rods will then further degenerate to cause daytime blindness.

Bumping Into Objects

Dogs that are starting to lose their ability to see may bump into objects that aren't normally in that specific spot. Stationery items or things that don't usually move around a dog's normal environment such as furniture and doorways are usually memorized so even blind dogs can navigate around them. But if a new coffee table is suddenly placed in the middle of a room, a dog with vision impairment may bump into it. If you bring your dog to an unfamiliar place, it may begin to bump into walls or other objects it can't see. In addition, Your dog may also begin to walk past or trip over its toys because it does not see them.

Difficulty Seeing in Bright Light

If a dog is developing PRA, you may be able to tell by your pet's reaction to bright light. As a result, your dog's pupils will be much more dilated than usual when shining a light in its eyes.

Unable to Follow Hand Signals/Commands

A dog with PRA won't be able to pick up on body language cues from other animals or see hand signals to obey commands.

Causes of Progressive Retinal Atrophy

Several breeds of dogs are prone to PRA. In some breeds, it seems to be restricted to male dogs while in others it appears to be due to a dominant gene and is seen in both sexes. Both purebred and mixed breed dogs can have PRA. Predisposed breeds that may be afflicted with early or late-onset GPRA include:

  • Akita
  • Alaskan malamute
  • American cocker spaniel
  • Belgian shepherd
  • Briard
  • Cardigan Welsh corgi
  • Collie
  • Dachshund
  • English cocker spaniel
  • Glen of Imaal terrier
  • Irish setter
  • Labrador retriever
  • Mastiff
  • Miniature schnauzer
  • Papillon
  • Poodle (miniature and toy)
  • Portuguese water dog
  • Samoyed
  • Siberian husky
  • Tibetan spaniel
  • Tibetan terrier

Breeds that may be afflicted with the rarer CPRA include:

  • Border collie
  • Golden retriever
  • Labrador retriever
  • Shetland sheepdog

Diagnosing Progressive Retinal Apathy in Dogs

Your vet will want to rule out other causes of blindness and may refer you to a specialist. PRA is typically diagnosed by your vet, or a veterinary ophthalmologist, with an electroretinography test. This test measures the electrical responses of your dog's eyes to determine if it has PRA.

Treatment

There is currently no effective treatment for PRA in dogs. If cataracts have developed as an associated complication of PRA, it is typically not recommended to remove them because it will not help or improve the dog's sight.

Further research into gene therapy may offer dogs with PRA a cure by introducing a normal copy of the CNGB1 gene (the gene associated with the disease), but this is not presently a widely available therapy or cure.

Prognosis for Dogs With Progressive Retinal Apathy

Eventually, a dog with this eye disease will go blind. This is not a painful disease, so helping a pet navigate its new environment as it loses its vision is your best course of action if gene therapy is not an option. The layout of furniture should not change in a dog's home, blind dogs should be kept on a leash at all times when outside, and extra care should be taken when walking a blind dog to ensure it does not run into walls or other objects. You may want to get your dog a halo for further protection in its environment.

How to Prevent Progressive Retinal Apathy

Since it is a hereditary disease, progressive retinal atrophy is something that dogs can be born with if their parents had it. Selective breeding should be performed to eliminate dogs showing signs of PRA from the gene pool. There may also be a DNA test available for your dog breed to help identify if it is a carrier of the disease.

Article Sources
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