Symptoms of PRA
Although the types and expressions of the forms of Progressive Retinal Atrophy do vary in severity and age of onset, the common symptoms are progressive vision loss, almost always beginning with a loss of night vision, as the disease affects the rods first. As night vision deteriorates, the dog will typically exhibit behavioral signs, such as disorientation at night, apprehension around stairs or new environments in dim light, or literally getting lost in their own home, especially if the furniture has been rearranged. Physiologically, affected dogs will typically have excessively dilated pupils at night, as their eyes are trying to let in more light. Additionally, there may be a noticeably greater shine to the eyes at night, as the pupils dilate excessively and the retinal tissue thins, exposing more of the reflective rear surface of the eye.

Diagnosis of Progressive Retinal Atrophy
Preliminary diagnosis is typically via fundoscopic exam (with an ophthalmoscope) by a licensed veterinary ophthalmologist. This exam is painless and requires no sedation, but the pupil must be dilated. The vet would be looking for blood vessel shrinkage, increased reflectivity of the tissue behind the retina, decreased pigmentation of the retina, and a darkened optic disc in advanced stages. However, secondary cataract formation, which may occur with the disease, may make examination difficult. Additionally, depending on the breed and type of Progressive Retinal Atrophy, these symptomatic changes may not occur until later in life when the disease begins to manifest, so a clear exam in a puppy does not guarantee they are free from the disease.

Often, though, a dog will already have exhibited signs of the disease, like night vision loss, by the time a fundoscopic exam would clearly identify PRA.

However, a more accurate assessment can be made via an electroretinogram (ERG), which is an electrical evaluation of the response of the retina to varying flashes of light and color. This procedure does require sedation, as it involves placing a type of contact lens over the eye. This procedure is sensitive and accurate enough to detect changes in the retina, often before the vision has deteriorated to the point that the dog shows signs of Progressive Retinal Atrophy.

Treatment of Progressive Retinal Atrophy
There is no treatment for PRA, and no known way to slow the progression. Generally, it eventually progresses to blindness. There have been some studies on the use of Vitamin A therapy on the human parallel disease, retinitis pigmentosa, but no studies have been done to date on vitamin therapy in dogs.

Breeds Affected by PRA
Following are some of the breeds affected, type of PRA common within the breed, age of onset, genetic mode of inheritance, and presence of a genetic marker test for the breed.

Breeding Decisions
Dogs affected with PRA should obviously not be allowed to breed, and should be neutered or spayed. Since Progressive Retinal Atrophy is inherited genetically, parents and siblings of PRA-affected dogs should also not be bred, in the absence of complete genetic evaluation. Fortunately, with precise genetic tests now available for many breeds, affected and carrier dogs can be pinpointed prior to breeding decisions.

Contact us at voyagereskies@yahoo.com

WEB Space hosted by http://ToyDogSites.com 
WEB and graphic designs by "Design with Christy"
for help on this site or information on creating your own site email Christy