Veterinary ophthalmologists have identified a condition of rapid onset of blindness. This condition, known as Sudden AcquiredRetinal 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.
Have any questions on this subject? Contact
Dennis Hacker via E-mail:
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