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.
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.
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
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
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.
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
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