CANINE PROGRESSIVE RETINAL ATROPHY

CODE: C104

INTRODUCTION:
HEALTHGENE LABORATORY IS APPROVED BY THE ORTHOPEDIC FOUNDATION FOR ANIMALS (OFFA) FOR CANINE PROGRESSIVE RETINAL ATROPHY.

DESCRIPTION
Canine Progressive Retinal Atrophy (PRA) refers to a broad group of inherited, and sometimes acquired, retinal conditions which will eventually result in the blindness of the dog. Due to the nature of this disorder, and the fact that it does not always have noticeable symptoms until it is relatively advanced, repeated examinations might be required to detect the animal with PRA. Dogs that have been affected and diagnosed with Progressive Retinal Atrophy should not be used for breeding purposes. Should the dog be fighting a viral or bacterial infection, it will be reflected in the general health of the animal's eyes. The eye, particularly the retina, is dependant on a supply of blood to keep it fed and healthy. If the blood supply becomes contaminated with a virus, bacteria or toxin, the eyes are like window to the state of the body, and changes within the eye can be observed and these are often important in making a diagnosis of an illness. The retina is a highly complicated tissue located at the back of the eye. Light strikes the retina and starts a series of chemical reactions that causes an impulse. The impulse passes through the layers of the retina to the optic nerve, and from there to the brain where vision takes place. In the retina, cells called rods are involved with black and white, or day vision. Progressive retinal degeneration may affect the rods alone, the cones alone, or both the rods and cones together. PRA should not be confused with dysplasia which is a blindness caused by the abnormal development of the retina. Progressive Retinal Atrophy is the slow death of retinal tissue and the owner may overlook the earliest signs. PRA is not a painful condition - there are neither reddened eyes nor any increase in blinking or squinting. Sometimes what happens is the owners may notice an abnormal "shine" coming from their pet's eyes. This abnormal shine occurs because the pupils are dilated and don't respond as quickly to light as the pupils of a normal dog. Some dogs will seem disoriented when going out to the yard at night; the owners end up leaving a light on for them. Night blindness may be observed in a dog that is afraid to go into a dark room. Occasionally, these dogs will get lost in their own home after the lights have been turned off. Night vision difficulties, in most cases, will progress to day blindness as well.

INHERITANCE
Canine Progressive Retinal Atrophy shows an autosomal recessive mode of inheritance; therefore two copies of the defective gene, one inherited from each parent, have to be present for a dog to be affected by the disease. Dogs 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.

DNA TEST
This DNA test provides reliable identification of dogs that carry mutant gene(s). The DNA test allows a breeder to control the mutant gene frequency in Irish Setter and Cardigan Welsh Corgi breeds, thus preventing the production of puppies affected with Canine Progressive Retinal Atrophy. This DNA test accurately and specifically identifies normal, carriers (heterozygous) and affected dogs.

BREEDS:
Cardigan Welsh Corgi
Irish Setter

TEST RESULTS: