Progressive Retinal Atrophy (PRA) in DogsProgressive Retinal Atrophy is an eye disease that can occur in very many breeds of dogs, but some breeds of dogs, such as the Poodle, are more susceptible to it than others. PRA is hereditary. Occurs in different forms. What symptoms should I look out for and when is it better to go to the vet? What is the course of the disease. What should I know about it? Unfortunately, there are secondary diseases for which a dog suffering from PRA should be regularly examined.
If your dog does not catch treats well, he may have eye problems
Progressive retinal atrophy in dogs
Progressive retinal atrophy (PRA) is a hereditary eye disease in dogs, which can occur in many breeds of dogs. PRA stands for a whole group of genetic diseases of the eyes, which are caused by pathological changes in the retina and can sooner or later lead to complete blindness.
PRA always affects both eyes of the dog. The retina contains the cells that are important for the visual process, namely the rods (night vision) and cones (day vision and colors). Often the rods are affected first, leading to night blindness, and as the disease progresses, the cones are affected as well, leading to progressive blindness.
Almost every dog breed can be affected by PRA, but there are different forms, which break out at different times in the dog breeds and are inherited differently. Therefore, there are currently different genetic tests available for progressive retinal atrophy (PRA) in dogs in Germany, depending on the dog breed. The Clinical Diagnostic Laboratory LABOKLIN has an overview of gene tests for PRA.
This is how progressive retinal atrophy manifests itself in dogs
The symptoms of Progressive Retinal Atrophy and their time of onset depend on the breed of dog and the form of Progressive Retinal Atrophy:
Early onset of PRA (Generalized PRA – early-onset)
In this variant of PRA, the cells of the photoreceptors (visual cells such as rods and cones) of the retina develop pathologically and continue to degenerate in the first weeks after the puppy's birth. The first symptoms of this form are usually night blindness at the early age of 6 weeks, which develops into total blindness by 1-2 years of age.
However, depending on the breed of dog, this form develops differently both in time and in symptoms. Collies can often maintain their vision for longer, i.e. until the 2. up to 3. Preserved until the age of 18. Night blindness often only after the age of 6.Month. Blindness only at the age of 3-4 years.month and blindness only at 3-4 years of age. At Alaskan Malamutes day blindness develops at 8-10 weeks, but night blindness usually does not develop at all.
Late onset of the disease (Generalized PRA – late-onset)
Slow development of the disease (Central PRA – slow development)
Diagnosis of progessive retinal atrophy in dogs
Progressive retinal atrophy does not usually manifest itself in obvious, externally visible changes in the eyes. At the beginning, the dog owner may notice that their dog is having difficulty finding his way in the dark. Whether it is that the dog begins to bump into objects in the house or shows insecurities when walking in the dark, which did not exist before.
So, if you suspect any impairment in your dog's vision, it is generally advisable to consult a veterinarian. It is best to choose a veterinarian who specializes in ophthalmology or get advice from your family veterinarian. The veterinarian can use an ophthalmoscope to examine the eye for abnormalities and detect progressive retinal atrophy.
PRA can also be detected using an electro-retinogram (ERG) long before the dog shows any ocular impairment. ERG is an examination of the retina using light stimuli that are sent to the retina and measured by electrodes. This examination is usually found only in specialized clinics.
There are genetic tests for the different types of PRA that can occur in different breeds of dogs. These tests are useful for breeders to exclude Progressive Retinal Atrophy carriers from breeding. For dog breeds that are predisposed to this eye disease, it is advisable to ask the breeder in advance whether these tests have been done on the breeding dogs in advance. Unfortunately there is no therapy yet. Treatment of progressive retinal atrophy. Neither medication nor surgery can stop the disease. It can only be controlled in the future by appropriate genetic testing and breeding exclusion of the dogs that carry the gene.
For the form of PRA, which is inherited via X-chromosomes, so-called gene therapies are said to have brought first successes in research. However, these are still in an early stage of research (as of January 2020) and only apply to corresponding dog breeds in which PRA is inherited via the X chromosomes. This includes z.B. Huskies and Samoyeds.
The degree of impairment of the dog's vision varies greatly depending on the breed and the type of PRA, but most affected dogs eventually go completely blind sooner or later.
However, since the disease develops progressively, i.e. mostly slowly increasing, the dog has the possibility to adapt to this condition. Dogs have both a well-developed sense of smell and a well-developed sense of hearing, which enables them to compensate relatively well for the lack of eyesight.
In case of blindness you can support your dog by z.B. choose familiar walks with the same routes for him, expose him to familiar environments only if possible, and introduce him to changes piecemeal. And of course you should be patient with your dog.
A not uncommon secondary disease is cataract, which can lead to clouding of the lens and also to blindness. Since glaucoma (increased intraocular prere) can occur as a result of cataracts, annual eye examinations of dogs with PRA are very important. Glaucoma needs to be treated as it can be very painful and if left untreated can lead to loss of the eyeball.
What are the causes of progressive retinal atrophy in dogs??
You do not have the possibility to prevent Progressive Retinal Atrophy in your dog.
Since it is a genetic defect, it can only be eliminated more and more from future litters through breeding selection.
PRA is genetically inherited differently depending on the dog breed with the following variants:
– In most cases, progressive retinal atrophy will be autosomal recessive inherited, which means that the disease only breaks out if it is present on both chromosomes. If it is only on one chromosome, PRA does not break out, but the dog is a carrier of the gene and can inherit it. – PRA is found in very few breeds such as z.B. Mastiffs and Bull Mastiffs autosomal dominant So there are no carriers of the disease, as they are either affected or not affected. This is a form of the disease that does not occur until later in life, in which the loss of vision occurs late in life. – Only in very few dog breeds this eye disease is transmitted via the X chromosomes inherited, such as z. B. with Huskies. Samoyed. in huskies and Samoyeds. These are the first gene therapy results in research.
Increased incidence in the following dog breeds
PRA is more common in these dog breeds than in others
Progressive retinal atrophy can basically occur in one form or another in any breed of dog. Nevertheless, it is more common in certain dog breeds than in others. In the respective dog breeds there are also different forms of inheritance and therefore different genetic tests.