Sudden acquired retinal degeneration
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Sudden acquired retinal degeneration (SARD) is a disease in dogs causing sudden blindness. It can occur in any breed, but female dogs may be predisposed.[1] Approximately 4000 cases are seen in the United States annually.[2]
The cause of SARD is considered to be idiopathic, but possibly involves either autoimmune disease, a toxin, or Cushing's disease.[3] Symptoms include sudden permanent blindness (sometimes developing over several days),[4] dilated pupils, and loss of the pupillary light reflex. Other symptoms commonly seen are similar to those seen with Cushing's disease and include increased water consumption and urination, weight gain, and lethargy. These symptoms may develop over a few months preceding the onset of SARD.[5] Despite similar symptoms and blood test results to Cushing's disease, evaluation of dogs with SARD did not reveal any tumors in the pituitary or adrenal glands.[6] Autoimmune disease as a cause has also been called into question because of a lack of antiretinal autoantibodies in dogs with SARD in one study.[7]
Examination with an ophthalmoscope will initially show no changes, but in a few months atrophy of the retina will resemble the appearance of progressive retinal atrophy. Pathologically, there is a loss of the rod and cone cells followed by degeneration of other layers of the retina. The retinal degeneration appears to be related to apoptosis of these cells.[8] SARD must be distinguished from other causes of sudden blindness that have no visible pathology, including retrobulbar optic neuritis, a tumor at the optic chiasm, or other central nervous system diseases. Electroretinography is useful to definitively diagnose SARD.[9] Currently there is no approved treatment, although the use of intravenous immunoglobulin has been investigated due to similarities between SARD and human immune-mediated retinopathy.[2]
[edit] References
- ^ Cullen C, Grahn B (2002). "Diagnostic ophthalmology. Acute prechiasmal blindness due to sudden acquired retinal degeneration syndrome". Can Vet J 43 (9): 729–30. PMID 12240536.
- ^ a b "Some blind dogs may get chance to see again" (July 2007). DVM: 1S. Advanstar Communications.
- ^ Gelatt, Kirk N. (ed.) (1999). Veterinary Ophthalmology, 3rd ed., Lippincott, Williams & Wilkins. ISBN 0-683-30076-8.
- ^ Sudden Acquired Retinal Degeneration (SARD). The Merck Veterinary Manual (2006). Retrieved on 2007-03-11.
- ^ Ofri, Ron (2006). Examination of the Blind Animal. Proceedings of the 31st World Congress of the World Small Animal Veterinary Association. Retrieved on 2007-03-11.
- ^ Gilmour M, Cardenas M, Blaik M, Bahr R, McGinnis J (2006). "Evaluation of a comparative pathogenesis between cancer-associated retinopathy in humans and sudden acquired retinal degeneration syndrome in dogs via diagnostic imaging and western blot analysis". Am J Vet Res 67 (5): 877–81. doi:. PMID 16649924.
- ^ Keller R, Kania S, Hendrix D, Ward D, Abrams K (2006). "Evaluation of canine serum for the presence of antiretinal autoantibodies in sudden acquired retinal degeneration syndrome". Vet Ophthalmol 9 (3): 195–200. doi:. PMID 16634935.
- ^ Miller P, Galbreath E, Kehren J, Steinberg H, Dubielzig R (1998). "Photoreceptor cell death by apoptosis in dogs with sudden acquired retinal degeneration syndrome". Am J Vet Res 59 (2): 149–52. PMID 9492927.
- ^ Gilger, Brian C. (2006). Diagnosis and Treatment of Ocular Fundus Disorders of Geriatric Dogs (PDF). Proceedings of the North American Veterinary Conference. Retrieved on 2007-03-11.
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