Mary Allen
Progressive retinal atrophy (also abbreviated as PRA) is an inherited eye disease that gradually leads to the death of the retina. Affected dogs go blind in both eyes over a longer period. There are no therapy options – that’s why genetic tests are particularly important in dog breeding.
For many dog owners, the first signs of incipient blindness come as a shock: how should things continue? And what did you just do wrong? However, injuries or a poor lifestyle do not always lead to eye diseases. Unfortunately, the cause of vision loss is sometimes programmed into a puppy’s genes at birth. Progressive retinal atrophy (PRA) is a group of such genetic eye diseases that unfortunately lead to complete blindness in affected animals (dogs and cats).
Cause of the PRA
As already mentioned, there are no external causes for progressive retinal atrophy. These eye diseases are inherited from the affected animals and, depending on the type of disease, can occur as early as puppies. In dogs, this disease is found in the gene pool of many dog breeds, in cats, the Somali and Abyssinian breeds are mainly affected. In most cases, it is an autosomal recessive gene that can cause PRA. This means that a puppy does not necessarily have to have PRA if one of the parents carries the gene.
In mastiffs, however, the gene is inherited dominantly, and in the Siberian Husky and Border Collie, the gene is linked to the X chromosome. The different types of genes that carry PRA make research and development of a genetic test difficult. There are already working test kits for the dog breed Irish Setter, Welsh Corgi Pembroke, Sloughi, Bull Terrier, Mastiff, and Bullmastiff. Therefore, reputable breeders of these dog breeds should always be able to present a certificate as to whether the parent animals are gene carriers or not.
The course of the Disease
Progressive retinal atrophy, as the name suggests, affects the retina of the eyeball. The retina forms the innermost layer of the fundus of the eye, in which the photoreceptor cells that are essential for sight, the rods and cones, are embedded. Rods are responsible for optically distinguishing between light and dark (night vision), and thanks to the cones, colors can be distinguished (day vision). In PRA, this retina and the photoreceptor cells embedded in it begin to die as soon as the gene is triggered. This marks the beginning of slowly progressive total blindness. In most cases, the rods degenerate first, leading to blindness at night. After that, the cones also deteriorate, and affected dogs can no longer see even during the day.
First Signs & Symptoms
Because progressive retinal atrophy progresses slowly, it is usually diagnosed at a very late stage. The first signs usually appear between the ages of one and six and only include the typical night blindness. This means that the dogs move very cautiously and uncertainly, especially at night. In addition, lens opacities (also called cataracts or cataracts) can also occur in the eyeball. After that, the dogs’ daytime vision also suffers, and eventually, they become completely blind in both eyes. Unfortunately, PRA always affects both eyeballs. Electroretinography (ERG) is the best way to register changes in the retina. The electrical potential of the neuronal impulses of the photoreceptor cells is measured to determine whether they are still functioning.
Prognosis: Is Progressive Retinal Atrophy the End?
Unfortunately, there is no way to cure progressive retinal atrophy or save the eyesight of diseased dogs. To take action against these eye diseases, it is therefore of immense importance to subject as many breeding animals as possible to a genetic test – as long as this is available for the breed, of course. This is the only way to ensure that PRA can occur less and less frequently.
However, complete blindness does not mean the end of the world! Dogs that are blind can also live full and happy lives if you pay attention to their visual limitations. As a guide for the blind, you have to pay more attention to the special needs of the animals and, for example, put them on a leash for a shorter time and warn them of obstacles. The most important thing for blind dogs is stability – this means that you should avoid rearranging the rooms or furniture if possible. Because especially in your own four walls, even dogs without sight find their way around surprisingly well. Playing with other dogs is also still possible – as long as the other dogs are considerate and your four-legged friend visibly enjoys the interaction.
There are many great examples of wonderful dogs living their lives to the fullest despite their blindness!