Progressive retinal atrophy (or PRA) in dogs is a slowly developing disease of the eyes that leads to eventual blindness after a period of months or even years. It is an inherited condition that is not contagious and not transmissible between different dogs, and one that certain breeds and types of dogs are more prone to than others. For dogs of some breeds that are particularly prone to the condition, DNA testing of the potential parent dogs can be carried out to confirm or deny the potential presence of a predisposition to the condition, and dogs that carry elevated risk factors for PRA should not be used for breeding. Test results for parent dogs are usually made freely available to would-be puppy buyers who are considering buying a puppy from a breeder who has already health tested the dam and/or sire.
The condition is genetically inherited, and no external stimulus or risk factors can trigger or prevent the development of the condition. It causes the retina of the eye, the part of the eye that acts as the camera lens to the world, to degenerate over time, eventually leading to blindness. The condition affects both eyes, and is not painful for the dog.
Any dog that has inherited the potential genetic predisposition for PRA may eventually succumb to the condition, and this includes mixed breed dogs and mongrels that have the ancestry of a dog that carries the mutation. Some of the breeds that are particularly prone to the condition include the Poodle, the Labrador, the Akita, the Cocker Spaniel, the Papillon, the Samoyed, the Tibetan Terrier, the Tibetan Spaniel, and the Husky.
The condition normally begins to develop and show signs in adult dogs, generally between the ages of around three and eight years old. The first indication for many owners is that the dog begins to lose its night vision, and have problems seeing obstacles or finding their way around in low light and darkness. As the condition progresses, the dog’s pupils may appear dilated, and take on the signature shining appearance that characterises the condition. Cataracts may also develop simultaneously with the condition, leading to a milky or clouded appearance of the lens of the eyes in some cases too.
PRA develops relatively gradually, and can take months or even years to progress to full blindness, meaning that dog owners are often unaware of the condition until it is quite advanced. Many dogs adjust to their progressively failing vision very naturally, and do not appear to run into serious difficulties, or become able to accommodate for their progressive blindness using their other senses, which again can make the condition hard to identify with ease.
When PRA is suspected in a dog, your vet will need to make a formal diagnosis of the condition. This will involve taking a full history of what has occurred from the owner of the dog, considering the dog’s genetic history, and examining the eyes themselves with an ophthalmoscope. If the eyes are clouded with cataracts as well as affected by PRA, this can make physical examination of the eyes difficult, and may necessitate an electroretinogram scan under a general anaesthetic. Your vet may also decide to refer your dog to a special canine ophthalmologist for a definitive diagnosis of the condition itself and its progression and severity.
Sadly, progressive retinal atrophy in dogs is not reversible or curable, and there is nothing that can be done to correct the blindness that accompanies the condition. Some vets recommend antioxidant therapy to attempt to prolong the dog’s vision for as long as possible and slow down the progression of the disease, but there is no definitive treatment or cure. Feeding an antioxidant rich diet to dogs throughout the course of their lives may prove helpful at slowing the progression or onset of the condition and various other ailments as well.
Currently, research is being undertaken into gene therapy for animals with PRA, although at time of writing this is still very much in its formative stages, and not a possible treatment option for currently affected dogs.
As the condition progresses to full blindness, the dog owner will need to make various accommodations for their dog’s failing vision, such as using only vocal cues and commands when training, and ensuring that the dog is kept on a lead at all times when near the roads or other hazards. Blind dogs require stability and consistency within their homes, in order to orient themselves and find their way around safely and without stress. This means that any upheavals in the home, such as moving furniture around or moving home entirely, should be avoided if at all possible.