The retina can degenerate because of elevated pressure in the eye (called glaucoma), from inflammation (chorioretinitis), or due to a genetic defect (called Progressive Retinal Atrophy or PRA).
From birth it takes 6 weeks for a retina to fully develop. Progressive Retinal Atrophy in dogs can happen before six weeks (early onset PRA) or later in life (late onset PRA). In PRA vision is first lost at night and then during the day.
Sudden retinal degeneration results in significantly faster sudden loss of vision with the vision being lost in 1 to 2 days.
SARDs or Sudden Acquired Retinal Degeneration has other names including "toxic neuroretinopathy", "metabolic toxic retinopathy", and "silent retina syndrome".
Some SARD's patients show signs suggesting hyperadrenocorticism (Cushings Syndrome), while others show signs of liver disease. SARDS has been identified in many breeds, and is more common in older purebred dogs.
Symptoms of Retinal Degeneration
Symptoms of dog retinal degeneration include lethargic or weak behavior, weight gain/obesity, increased urination (polyuria), abnormal levels of thirst (polyplasia) and increased hunger.
Diagnosis of Canine Progressive Retinal Degeneration
A clinical examination at your veterinarians office will find symptoms such as blindness in the eye and fixed dilated pupils.
The eye may change in appearance over time and testing will show no activity in the retina (ERG test).
Treatment of Retinal Degeneration in Dogs
Currently there is no treatment for PRA or SARDs and the blindness it causes is permanent, unfortunately.
Many research efforts are underway to fight this
Blindness in veterinary ophthalmology:examination, causes and treatment
Ron OfriMed Vet, PhD, Dipl ECVO, Rehovot, Israel
Diagnosis and Treatment of Ocular Fundus Disorders of Geriatric Dogs
College of Veterinary Medicine
North Carolina State University, Raleigh, NC