SUDDEN ACQUIRED RETINAL DEGENERATION
SARD
Veterinary ophthalmologists have identified a condition of
rapid onset of blindness. This condition, known as Sudden Acquired Retinal
Degeneration
(SARD), may strike any breed of dog. In some patients there are increases
in appetite and water consumption. Pets who develop SARD are often older
than 6 years of age. Examination of tissue specimens from some patients
at research institutions has indicated that the retina in these pets is
totally destroyed and cannot regenerate. Blindness occurs essentially overnight.
A typical pet would have gone out on a walk with the client one day or
evening and been normal. The next day, the patient would begin to bump
into everything in the house. Examination by a Veterinary Ophthalmologist
reveals that the patient has normal eyes with no evidence of significant
cataract development and no evidence of apparent retinal disease. The pupils
will occasionally, but not always, respond to light but the patient is
blind! Because there are no ophthalmic findings which indicate SARD, patients
with apparently normal eyes and acute vision loss should have blood tests
performed to rule-out systemic disease as a cause of blindness. The non-systemic
conditions which can mimic SARD are brain tumors and optic nerve inflammation
(optic neuritis). The reason the diagnosis is important is that if systemic
disease or optic neuritis is causing the blindness medication may restore
vision. If a brain tumor is determined to be present, then radiation therapy
may be necessary to save your pet's life. For these reasons, finding the
cause of sudden blindness is important! The first step in diagnosing the
cause of blindness is a thorough ophthalmic and physical examination and
blood tests. Next, a test of the retina known as an electroretinogram (ERG)
should be performed. If the retina is working normally, then further tests
are needed to determine the diagnosis. As with other types of retinal degeneration,
SARD has no treatment. Although veterinary ophthalmologists do not completely
know the cause of and cannot treat SARD, you should know that this is not
a painful condition. Your pet is not in pain. Your pet is just confused
as you would be if you suddenly went blind. How you should treat a blind
pet is the subject of another handout. |
