Nasreen's Dachshunds

Progressive retinal atrophy (PRA) is a term for retinal degenerations occurring in many breeds of dog. Many forms of PRA exist, each form being confined to one or a few breeds only. The disease results in a degeneration of the light-sensitive membrane at the back of the eye - the retina - resulting in loss of vision, and often leading to blindness.

The form of the disease occurring in miniature long-haired dachshunds can be diagnosed by electroretinography at a few months of age, although obvious clinical signs take longer to develop. The exact course of the disease can vary between individual dogs, and some don’t develop symptoms until relatively late in life.

The disease is caused by a change to a gene involved in sight. This change, or mutation, occurred spontaneously, but once in the population has been inherited from generation to generation like any other gene. The mutation upsets the delicate processes involved in vision and causes the long-term degeneration seen. This form of PRA shows an autosomal recessive mode of inheritance: two copies of the defective gene (one inherited from each parent) have to be present for a dog to be affected by the disease. Individuals with one copy of the defective gene and one copy of the normal gene - called carriers - show no symptoms but can pass the defective gene onto their offspring. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will be carriers

There is currently no treatment for the disease. Breeding stock are regularly checked by eye examination, although this can only pick up affected dogs after symptoms have developed and will never detect the symptomless carriers.

The gene responsible has been identified at the Animal Health Trust and we have recently identified the mutation causing the disease. Using the information from this research, we have developed a DNA test for the disease. This test not only diagnoses dogs affected with this disease but can also detect those dogs which are carriers, showing no symptoms of the disease but producing affected pups. Under most circumstances, there will be a much greater number of carriers than affected animals in a population.

Cord 1 PRA test results identify dogs as belonging to one of three categories:

NORMAL or CLEAR: The dog has two normal alleles and is free of the defect. These dogs will never develop PRA, nor pass a copy of the PRA gene to any of its offspring.

CARRIER: The dog has one normal allele and one affected allele that causes PRA.  These dogs will never have symptoms or develop PRA, but will pass on the PRA gene to 50% (on average) of its offspring.

AFFECTED: The dog has two copies of affected alleles and is affected with PRA. It is likely to develop PRA at some stage during its lifetime, and will pass the PRA gene to 100% of it's offspring.

Carriers can still be bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affecteds produced from a clear/carrier mating. However, it is important only individuals committed to PRA testing breed carriers since they represent a hidden reservoir of the disease that can produce affected dogs at any time. Breeding any non-clear dog requires complete testing of the entire litter and then sorting those into breeding (PRA clear) and non-breeding puppies (PRA carrier). Many breeders are not PRA testing their breeding dogs and therefore selling dogs with Full AKC who may be carriers to unsuspecting people who in turn breed the carrier to another carrier, potentially resulting in someone buying a puppy affected with PRA. 

At Nasreen's Dachshunds, we are taking the extra step and testing all of our dogs and puppies. We will know their individual PRA results before a breeding pair or new home is matched. Puppies who test as carriers may be available on full AKC, but strictly to approved homes ONLY. Please contact me for more information. 

It is very important to do your research before you buy a new puppy. If you have any questions regarding PRA or other genetic tests, please do not hesitate to ask. Thank you!