Congenital stationary night blindness (csnb), also called hereditary retinal dystrophy, in dogs is a recessively inherited retinal disorder (a defect in the gene RPE65) that affects the Briard dog breed. Dogs with this condition will experience night blindness and have various degrees of impairment in their vision during daylight. Some dogs that have congenital stationary night blindness will experience very little impact on their vision. 

Fortunately, the condition is not painful or dangerous and dogs that are minimally affected typically experience a relatively normal quality of life. Some dogs become completely blind as a result of the condition, which will usually be evident when they are very young.

Also known as hereditary retinal dystrophy, congenital stationary night blindness is due to a defect in the gene RPE65 in Briards, leading to night blindness and some degree of visual impairment during daylight.

Should your dog be experiencing congenital stationary night blindness, he will not be able to see at night and will possibly experience a range of other issues with his vision. The condition can cause permanent and irreversible blindness, though the condition will present differently in every affected dog. 

As the condition is hereditary, it cannot be caught like a virus. A dog can inherit the condition if two dogs that are either affected or are carriers of the gene mate and have offspring.

Congenital stationary night blindness occurs when there is a mutation in the retinal pigmentation of your dog’s eye in one of the protein genes. This will lead to dysfunction in the retina and cause lipids in the retinal pigmentation to accumulate, usually around the tapetum lucidum, which is the part of the eye that will reflect light. 

In order for your dog to inherit the disease, two copies of the defective gene (one from each of your dog’s parents) would have to be passed down to him. If your dog only has one copy of the gene, he would be a carrier, meaning he will not have symptoms of the disease but can pass it on to any offspring.

When two carriers of the gene mate, on average 25% of their offspring will inherit the disease itself and an additional 50% of their offspring would be carriers of the gene without symptoms of the illness.

Should you believe that there is something amiss with the vision of your dog, you will want to take him to your veterinarian, who will conduct a physical examination, including a vision test. Your veterinarian will likely ask you what you have noticed that has led you to believe that your dog may have an issue with his sight.

In addition to a physical exam, DNA testing for the disease is available. This may or may not be something that you are interested in pursuing, particularly if you are not planning to breed your dog. The DNA test will look at the RPE65 gene and provide information on whether your dog is affected by the disease or if he is a carrier without symptoms. If you are a breeder and are looking to breed a dog who is a carrier, you will want to be sure that he is bred with a dog that is not carrying the gene for congenital stationary night blindness.

There is no treatment for this condition. Should your dog be experiencing any vision impairments, your veterinarian can provide recommendations as to how you can assist your dog and accommodate his vision difficulties.

Should you be interested in breeding your Briard, it is recommended that he or she undergo DNA testing to determine whether they are affected by congenital stationary night blindness or are a carrier. Should they be a carrier of the gene that causes the disease, you will want to be sure that they only breed with a dog that is not a carrier of the gene, so as to not to pass the disease to their offspring. Their offspring could then become carriers of the faulty gene, and should be tested themselves prior to being bred.