What Is Progressive Retinal Atrophy (PRA) And How Can It Affect My Dog?
The condition known as progressive retinal atrophy (or just “atrocity” for short), or simply “retinopathy”, is a degenerative disease affecting the retina. The retina, which contains light-sensitive cells called photoreceptors, converts incoming light energy into electrical signals that are transmitted through nerve fibers to the brain. When these nerves become damaged, they no longer function properly and the brain cannot receive proper input from the eyes. The damage may occur anywhere along the retina, but it’s most commonly found in areas where there are blood vessels supplying oxygenated blood to the retina. These veins supply oxygenated blood to the photoreceptor cells located at those locations.
When such a vein becomes blocked with debris or other foreign material, it causes retinal hemorrhage. This results in loss of vision due to lack of blood flow to the photoreceptors.
If left untreated, the blindness may progress over time until eventually all visual functions have been lost. The condition is irreversible and death occurs within a few years after onset.
Atrocities are usually inherited, but occasionally mutations occur that cause them to develop spontaneously without any genetic predisposition. In some cases, however, the condition develops because of environmental factors such as exposure to certain chemicals or toxins.
In dogs, retinopathy is most often caused by a lack of vitamin A (hypovitaminosis A) in the diet. This is because the retina relies on carotenoids, which are converted into vitamin A by the body, for normal development and functioning.
Is There Treatment For Retinopathy?
Unfortunately, there is no permanent treatment or cure for this condition. Early detection is possible through regular eye exams, however, and your veterinarian can refer your pet to an ophthalmologist if the condition is found to be present. In some cases, surgery may be performed in an attempt to lower intraocular pressure and slow the bleeding process.
What Happens If My Dog Has Retinopathy?
The rate of disease progression is variable for each dog that has it. The most common sign of retinopathy is loss of visual acuity (perception of images). This is usually detected during an eye examination, and in these cases the condition is said to be “congenital” because the dog was born with it. Other common signs include night blindness, in which a dog has difficulty navigating in low-light conditions.
As the disease progresses, complete blindness develops and other signs may be seen. Many dogs begin bumping into objects and may exhibit signs of anxiousness.
Changes in hearing and a loss of balance may be seen as well. In some cases the dog will begin to walk in circles because it is having difficulty maintaining a clear picture of what is in its environment. Another sign of retinopathy is phthisis, in which there is a loss of sensitivity in the nose, ears and tail.
Can I Do Anything To Help My Dog?
The best thing that you can do for your dog is to take it to the veterinarian at least once a year for a complete check-up. Many eye problems don’t exhibit any outward signs until they’ve progressed past the point of repair. During the examination, the doctor will perform a thorough check of the eyes and may perform additional tests such as dilating the pupils to look at the retina more closely or testing the internal eye pressure. If the disease is detected early enough, surgical repair may be possible to prevent the development of blindness. Even if the dog has already lost vision before diagnosis, however, it may be able to adapt to this condition provided that it remains in a low-stimulus environment and is not expected to perform demanding tasks.
If you notice any of the signs listed earlier, contact your veterinarian as soon as possible. Early detection and treatment is vital to minimizing damage and maximizing your dog’s quality of life.
Sources & references used in this article:
cGMP phosphodiesterase-α mutation causes progressive retinal atrophy in the Cardigan Welsh corgi dog by SM Petersen–Jones, DD Entz… – … ophthalmology & visual …, 1999 – iovs.arvojournals.org
Late‐onset progressive retinal atrophy in the Gordon and Irish Setter breeds is associated with a frameshift mutation in C2orf71 by LM Downs, JS Bell, J Freeman, C Hartley… – Animal …, 2013 – Wiley Online Library
Natural models for retinitis pigmentosa: progressive retinal atrophy in dog breeds by M Bunel, G Chaudieu, C Hamel, L Lagoutte, G Manes… – Human Genetics, 2019 – Springer
A frameshift mutation in golden retriever dogs with progressive retinal atrophy endorses SLC4A3 as a candidate gene for human retinal degenerations by LM Downs, B Wallin-Håkansson, M Boursnell… – PloS one, 2011 – journals.plos.org
A CNGB1 frameshift mutation in Papillon and Phalene dogs with progressive retinal atrophy by SJ Ahonen, M Arumilli, H Lohi – PloS one, 2013 – journals.plos.org