Progressive Retinal Degeneration 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 may be required to detect the individual with P.R.D.  Dogs that have been affected and diagnosed with P.R.D. should not be used for breeding purposes.
        Some experts in the field of eye disorders, think that P.R.D. is an immune response problem.  Should the pet 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 windows to the state of the body, and changes within the eye can be observed and is 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 night vision.  The cells called cones are involved with color, or day vision.  Progressive retinal degeneration may affect either the rods alone, the cones alone, or both the rods and cones together.
         P.R.D. should not be confused with dysplasia which is a blindness caused by the abnormal development of the retina.  Progressive Retinal Degeneration is the slow death of retinal tissue and the earliest signs may be overlooked by the owner.  P.R.D. is not a painful condition - there are no 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.  Occassionally, these pets 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.
         P.R.D. will progress at different rates in different breeds.  This variation causes difficulty in determining just how long any particular dog will continue seeing.  It is imperative that your veterinarian be involved in the treatment of your dog, and in recommending an ophthalmologist.  Your dog can still lead a productive, involved and full life even when blind.  The decisions and responsiblity for the dog's life are up to the owner.