The most distressing thing for any pet owner to realize is that their pet is afflicted with a disease. And one of the most debilitating conditions that dogs and their owners have to face is Pra disease.
PRA disease or Progressive Retinal Atrophy Disease is a condition that causes the degeneration of the retina, with the eventual result being permanent blindness of your pet. The retina is comprised of cells called photoreceptors, of which there are two types: rods and cones. PRA disease first affects the rod photoreceptors, which helps your pet see in dim light. When PRA disease first strikes, you may notice your dog show signs of difficulty seeing in dim lighting conditions. PRA disease will affect the cone photoreceptors later on, and your pet may then have difficulty seeing even under brightly lit conditions.
Since PRA disease progresses quite slowly, most dogs will adapt to their condition by relying more and more on their senses of hearing and smell. This is why PRA disease so often remains undetected, and most pet owners are unaware that there is anything wrong with their dog until the disease has progressed to an advanced state. By this time, significant damage to the rod and cone photoreceptors will have already occurred.
PRA disease diagnosis is most often performed via an ophthalmic examination. In this test, a veterinary ophthalmologist will be able to detect PRA disease in its advanced stages by a retinal examination. If the disease is still in its early stages however, it will not be quite as easy to detect.
Another test that is used to detect PRA disease is called the ERG or electroretinogram. In this test, the veterinarian measures the electrical reaction of the retina to light stimulation. This test is more effective than an ophthalmic examination at detecting PRA disease in its early stages, although it requires more specialized equipment and a more experienced veterinarian. In addition, your pet will have to be placed under general anesthesia for the duration of the procedure. These requirements are primarily why electroretinography is more often used to confirm a suspected case of PRA disease than for early screening purposes.
The bad news for dogs suffering from PRA disease and their owners is that treatment procedures are virtually non-existent, since blindness resulting from the condition is permanent and there is no cure.