PRA – Genetic Blindness

 Progressive Retinal Atrophy is an inherited genetic disorder present in dogs at birth and ends in blindness as the dog matures. PRA slowly adds a film over the lens of the eye, similar to cataracts, restricting and finally stopping the flow of light into the eye. There are two versions of PRA, early onset and late onset.  The only difference between the two is the point in time when the disease shows itself.  

Early onset PRA is sometimes seen in puppies as soon as their eyes open. Pups have trouble seeing in low light or darkness. Oftentimes the owners think the puppy to be either uncoordinated or still developing and don't really notice that poor eyesight is the real culprit. As the puppy grows, the poor eyesight gets worse, especially in poorly lighted or dark situations. Usually puppies with early onset PRA will become totally blind before 5 years old, and many completely lose their vision within the first year.

Late onset PRA shows itself at any time after the first year with full blindness occurring at any time after the dog reaches three years old. Sometimes dogs with late onset PRA don't become completely blind or experience any vision loss until well beyond five years of age. Night blindness is generally the first sign as night vision starts to diminish. Dogs that are in light most of the time, an indoor pet for instance, may exhibit these early signs simply because the house is lighted in the evenings.

PRA is a recessive gene disorder in nearly all breeds, but there are exceptions. In the Siberian Husky and Samoyed lines the genes that cause the problem are linked to the animal's sex, in this case PRA is present only in the males. In the Old English Mastiffs and Bullmastiffs, however, PRA is the dominant gene.  Testing is constantly being done to try to determine the genetic placement in other breeds.

 PRA can be found in any dog, any size, any breed, including hybrids, designers and even good old mutts as long as both parents carried the genetic disorder.  

One a comforting thing to know is that PRA is neither painful nor uncomfortable.  It also will not cause any other neurological or health problems. Most of the dogs slowly losing their vision adapt and live fairly normal lives.  They are happy, well-adjusted dogs. Major safety concerns for these dogs include a fenced yard and not leaving the house without a leash for their own physical well being. Every dog should have its vision tested yearly.  Tests should be done prior to breeding for any vision problems including PRA. Researching the blood line for a history of PRA is also important.

Ongoing research is being done to find possible treatments for the impairment. Research results so far indicate that dietary supplements containing antioxidants may in fact slow down the vision loss, but it cannot stop the process or reverse damage already done. Additional research and close genetic testing before breeding may help eliminate this genetic disorder from breeding lines. 

Article by Kelly Marshall of Oh My Dog Supplies, check for current specials on big dog clothes online.