Progressive Retinal Atrophy
PRA refers to a group of clinically similar, inherited, blinding diseases of dogs. PRA-affected dogs all show the same sequence of clinical abnormalities in the course of the disease: night blindness, followed by progressive loss of day vision, and eventual blindness. When examined with a ophthalmoscope, the affected retina shows progressive thinning or atrophy, hence the name given to the disease.
Early-onset PRA: Some forms of PRA, such as that found in Irish Setters, develop very early and result in total blindness by 1 year of age.
Late-onset PRA: Other forms of PRA do not become clinically evident until the dog is about 3 years old. Late-onset PRA is found in Poodles, cocker Spaniels, Labrador Retrievers and other breeds.
It was long thought that the form of PRA peculiar to Miniature Schnauzers is of the late-onset type but, as a result of research published in 1991, it is now believed that the PRA found in Miniature Schnauzers is actually an early onset disorder in which the clinical manifestations are uniquely delayed. The ophthalmoscopic hallmarks of PRA are not apparent until very much later in life and unlike other early onset forms of PRA, visual function is only subtly affected in young affected animals. Vision remains relatively normal for many months to years. This type of PRA is photoreceptor dysplasia ("pd").
The American Miniature Schnauzer Club of American is funding research to isolate this gene which is being conducted at The Baker Institute at the College of Veterinary Medicine of Cornell University. Funds are need to continue this research. Donations can be sent to:
AMSC Fund Raising Committee
c/o John Hoffman
4035 Robin Hill Rd
Flintridge, CA 91011-3811
Source: Information obtained from "The AMSC PRA Project", The American Miniature Schnauzer Club
PHOTO CREDIT: Amy (on right) is currently 12 years old. She started showing first signs at age 7, when she became "night blind". She slowly lost her sight from there over the next two years or so. Amy was closely followed by Colorado State University Veterinary Hospital during her early days of PRA. Amy is loved by Rolf and Bobbi Baehr of Loveland, Colorado, USA who we express our appreciation for sharing Amy's photo with us.
PRA IN MINIATURE SCHNAUZERS
PRA stands for Progressive Retinal Atrophy. P.R.A. causes the retina of the eye to deteriorate slowly. Symptoms may not show until the dog is three years old or older, beginning with night blindness. P.R.A. eventually blinds the dog. It is incurable. An Electroretinograph can be used for early detection, but this tool is not available to most breeders. It is recommended that a annual eye certification of breeding stock be completed to reduce the risk.
As you may know the AMSC on October 7, 1994 had commissioned the James A. Baker Institute for Animal Health at Cornell University to develop a blood test which will detect the defective gene. This was a 3-year project. However, it looks like it may take longer. If you would like more information on this project, you may contact The American Miniature Schnauzer Club.
Posted by Tony V. AJVFRAC@aol.com
Links to PRA web sites: (click on a title to GO)
AMSC PRA Project
EyeVet - information on various diseases, including PRA
A PRA Primer (regarding the disease in Labrador Retrievers)
Progressive Retinal Atrophy (by Dr. Aguirre)
Veterinary article on PRA