Retina

the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve

Hypertensive Retinopathy

Hypertensive retinopathy, which can include small to extensive areas of retinal detachments and hemorrhage, is often controllable with oral medications. However, systemic hypertension is rarely curable and lifelong treatment is necessary.  (FAQ on Hypertensive Retinopathy)

Progressive Retinal Atrophy (PRA)

Generally, PRA is an inherited disease.  It is found in all breeds and even mixed breeds.  In most breeds, the disease is inherited by simple autosomal recessive mode.  Autosomal recessive inheritance requires one bad gene from the mother and one from the father.  Neither father nor mother has to have the disease but may simply be carriers. (FAQ on PRA)

Retinal Degeneration

The Retina is the part of the eye that receives light and an image and then sends electrical impulses to the brain.  Animals with retinal degeneration have dysfunction (impairment) or death of the cells in the retina and therefore have decreased or absent vision. (FAQ on Retinal Degeneration)

Sudden Acquired Retinal Degeneration

Sudden acquired retinal degeneration (SARD) is a condition where there is a sudden onset of vision loss due to a rapid degeneration of the cells of the retina that detect light (rods and cones). 

It is yet unknown why this condition occurs, but it is more common in middle-aged to older dogs (6 yrs and older).  Dogs affected by SARD often have additional signs such as increased drinking and urination, weight gain, and increased appetite.  These signs are very common in dogs with hyperadrenocorticism (Cushing’s disease) where the body is producing too much of its own cortisone (steroid).  As of this time, no one has proven a cause and effect relationship between these conditions.  Intense stress, such as that experienced with sudden blindness, may also cause many of these additional signs.  Recent research studies have supported the theory that SARD is due to an auto-immune retinal condition.  At this writing, treatment for SARD is in the experimental stage only. (FAQ on SARD)