| This is what Collies are all about. You will find no other breed with the love and loyalty that a Collie is willing to give to you and your family. |
| Original Site |
| Cornell University has discovered the DNA marker for PRA in Collies. Breeders will have a test for PRA in the near future!!! All of our dogs will be tested. The only way to test for PRA, previous to this test, was to locate PRA blind dogs to breed to your own dogs. This could produced puppies that were blind, if your dog also carried the DNA gene for PRA. This would mean eliminating dogs from your breeding program. If enough puppies were born and none of the puppies developed PRA, your dog was clear of PRA, but ALL the puppies would still be carriers of PRA, all capable of passing on the disease. This was very expensive to do, and difficult to find homes for puppies that would be blind the rest of their lives. Now, breeders will be able to do blood tests to determine the DNA status of their dogs. PRA is inherited as a recessive trait. This means a gene for PRA must be inherited from each parent for their puppies to have the disease. Dogs are either “carriers” or affected. A carrier has one disease gene and one normal gene and was not blind. A normal dog has no disease gene, was not blind, and would not pass along any PRA genes to its puppies. A dog with two genes for PRA would be blind, and would pass along PRA genes to some of the puppies. That is why this test is so important to breeders. Breeders will be able to test their dogs, and know which dogs are 'safe' to breed to other dogs, therefore, avoiding producing PRA blind dogs. Dogs that are PRA/Clear (no genes for PRA) can be bred to any other dog, even blind ones, and produce puppies that will never go blind from PRA. This also allows breeders to completely eliminate PRA from their bloodlines, which is the ultimate goal of conscientious breeders. So, this is a wonderful and important breakthrough for Collie breeders. Researchers have discovered this DNA marker gene in other breeds, and now Collies and their breeders will have the advantage of this new test, as soon as it becomes available to us. |
| Nc Normal/carrier (is not blind but carries 1 PRA gene & 1 Normal gene) |
| Possible PRA status |
| aa PRA Blind (carriers 2 genes for PRA) |
| NN Normal/Clear (carriers 2 normal genes) No affected genes. |
| One Parent, a Normal/Clear dog (no PRA genes) bred to another Normal/Clear dog will produce only PRA Normal/Clear puppies. (No blind or carrier puppies.) |
| One Parent, a Normal/Clear dog (no PRA genes) bred to a Normal/carrier (1 normal gene & 1 affected gene) will produce both Normal/Clear & Normal/carrier puppies. (No blind puppies.) |
| One Parent, a Normal/carrier bred to a Normal/carrier will produce Normal/Clear, Normal/carrier puppies and PRA blind puppies. |
| If both parents are affected (blind because they carry 2 genes for PRA) all the puppies will carry 2 genes for PRA and all will be PRA blind. |
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