One of the only known dogs to have a condition known as stationary night blindness, the Briard dog of Sweden is now in the cutting edge of DNA testing to determine a specific test to clearly identify carriers, affected dogs and non-affected dogs.
Stationary night blindness is characterized by various degrees of blindness in the Briard dogs that may become progressively more pronounced as the dog matures or may remain relatively constant. This variation can go from slight loss of vision in shadows or dark areas to almost complete blindness even in full light. Since the dog's will have temperament changes when they start to loose their vision this is often the first indication that there is something wrong with the dog. They may also have difficulty in moving around at night, which may gradually become more apparent in the day. In some cases full blindness occurs rather rapidly while in others the progression is relatively slow.
The cause of congenital stationary night blindness or CSNB is an autosomal recessive type of retinal blindness, which means that both parents must be carrying the gene for the offspring of the mating to develop stationary night blindness. Until genetic testing was available there was no specific way to predict if a Briard had the condition unless he or she was showing problems with vision. Now, with DNA testing, dogs can be checked prior to breeding to determine if the recessive gene is present. If the gene is present but was only inherited from one of the parents, the dog is considered to be a carrier. He or she will not show any vision problems from the stationary night blindness, but it would be able to pass this on to his or her puppies, which would be a huge concern if the other dog in the mating pair was also a carrier. With new genetic testing dogs can be marked as either carriers, having one recessive gene for the conditions, affected, having two recessive genes and therefore the condition, or non-affected, not having the gene for stationary night blindness. A carrier can be bred to a non-affected dog and produce a litter of puppies that would be free from the chance of developing stationary night blindness. Affected dogs and carriers cannot be bred together and neither can two carriers. Affected dogs are always spayed and neutered and not used in breeding programs by reputable breeders and owners.
Briard breeders are working diligently to try to breed out this problem. It is important to note the stationary night blindness is a very rare condition within the breed as is not considered to be problematic in most lines. There is ongoing research in both Briards and humans that have this rare condition and research is showing promising results for enhancing and even restoring vision lost through stationary night blindness.
|
