Progressive retinal atrophy (PRA) is an inherited disease and the most significant of genetic Miniature Schnauzer health problems.
PRA in dogs causes degeneration or breakdown of the retina inside the eye.
Since the retina is the part of the eye that senses visual information and sends it to the brain, its degeneration leads inevitably to blindness.
It lurks in the genetics of many breeds including: the Briard, Cardigan Welsh Corgi, Chesapeake Bay Retriever, English Cocker Spaniel, Irish Setter, Labrador Retriever, Mastiff, Poodle, Portuguese Water Dog, Samoyed, and Siberian Husky.
In Miniature Schnauzers, PRA does not normally develop until the affected dog is at least two years old.
The first sign of PRA in dogs is night blindness. This gradually progresses until the dog loses its sight altogether.
Diagnosis is by Veterinary examination of the eye. A special opthalmoscope is used to look inside the eye through the pupil, and see the retina that lines the back of the eye.
If Progressive Retinal Atrophy is present, there will be degenerating areas, or lesions, in the retina.
Affected dogs will eventually become completely blind. There are “echo-sensors” that can be fitted to dogs to teach them to find their way acoustically – yes.. the way bats do! But these are still in the trial stage.
Progressive Retinal Atrophy is a genetically recessive, inherited condition. That means a dog can carry it without ever being affected.
There are several genetic types of PRA in dogs, and Mini Schnauzers can get more than one of them. This makes it a complicated Schnauzer health problem, especially when it comes to the screening of breeding dogs.
At present, reputable Miniature Schnauzer breeders have their dogs’ eyes examined every year and only breed those that have visibly healthy retinas. The problem is that such testing doesn’t detect the dogs that are genetic carriers. A dog can’t be affected by the disease unless they inherit two genes for it – one from each of their parents.
If they only end up with one gene they will be carriers but not actually suffer from it. However, they can produce pups that suffer from it if mated to dog that is also carrying the gene(s) for PRA.
So even if the parents of your puppy both have clear “eye tests” this is no guarantee that it will not develop PRA.
Genetic tests are being developed that can detect the gene for PRA in dogs’ body cells (blood, semen etc).
Once fully available, these will allow breeders to properly eradicate PRA from their dogs, and will also be an effective option for puppy buyers who are willing to pay the costs to ensure their pup is clear of the risk.
When choosing a puppy, the first step is to make sure it is sourced from a breeder who tests their breeding dogs every year.
Ask to see their veterinary eye certificates and check that they are current.
However, as we explained, this is not a guarantee that it won’t develop PRA – it just reduces the risk.
Avoid inbred or line bred pups
Since any form of inbreeding greatly increases the chance of inherited defects of any kind showing up in puppies, the second thing to do is to scrutinize the ancestry or pedigree of any puppy you are considering to buy.
If you see the same dog’s name appear more than once in a pedigree RUN AWAY!!!
What is Line Breeding?
Amongst many “show breeders” it is common practice to “line breed” dogs.
In line breeding the same “Champion show dog” may appear up to three times in one pedigree – e.g. as dad, granddad (on mom’s side) and great-granddad (on dad’s side).
Show breeders rabidly defend this practice because it is a very effective way of establishing a line of show winners.
Line breeding is done to “improve the breed” – which literally means – increasing the extent that bred dogs conform to the “Breed Standards” for the breed.
But from a Veterinary point of view line breeding = inbreeding… no ifs, buts or maybes about it!!!
Any “bad genes” that exist in the “Champion” dog will be concentrated in the line every time he or is progeny appear in the pedigree. And that holds true not just for Progressive Retinal Atrophy, but for ANY inherited defect.
Outbreeding, by contrast, seeks to breed only unrelated dogs together – this dilutes any “bad genes” each may carry, and greatly reduces the chance that their offspring will inherit a pair of them and end up with an inherited problem.
Joe Average puppy buyers who just want a healthy, happy puppy are often better off sourcing their pup from a reputable “backyard” hobby breeder who is trying to produce healthy pets, not Show winners, and understands enough about genetics to avoid line breeding.