SARD (Sudden Acquired Retinal Degeneration) The symptom of this disease is blindness occurring suddenly or within a few days. Most commonly the disease is seen in middle aged female dogs (obese), but may be seen in other dogs as well. The Dachshund is overrepresented.
When the disease occurs, the pupillary light reflexes (pupil constriction after shining bright light into the eye) are still present in most dogs. The eye is blind and the ocular (ophthalmoscopic) examination reveals a normal looking retina at the onset of blindness. The photoreceptors (transmitters) in the retina (the back of the eye) suddenly die off. On microscopic examination of the eye, most layers of the eye are normal except these photoreceptors.
At the onset of blindness some dogs have increased thirst and appetite, and some initial studies indicated that dogs with SARDs may have increased cortisol levels. This increase is only temporary in most cases and unlikely associated with hyperadrenocorticism (Cushing’s disease). An ElectroRetinoGram (ERG) may be used by the veterinary ophthalmologist to determine how well the retina is working. The ERG allows the veterinary ophthalmologist to determine if the loss of vision is due to retinal, nerve disease (optic neuritis) or brain disease (inflammation, infection or cancer).
Most dogs with SARD have permanent blindness, although a few dogs seem to respond to anti-inflammatory therapy if treated early in the disease process. Prompt referral to a veterinary ophthalmologist is indicated in any case of sudden loss of vision.