Issue Description A disease in dogs causing sudden blindness. It
can occur in any breed, but female dogs may be predisposed.
Approximately 4000 cases are seen in the United States annually. Other Names Sudden Acquired Retinal Degeneration
Causes The cause of SARDS is considered to be
idiopathic and the veterinary community is divided as to its cause,
but the disease possibly involves autoimmune disease, toxins,
elevations in adrenal sex hormones or Cushing's disease.
Symptoms Symptoms include sudden permanent blindness,
but may occur more slowly over several days, weeks or months, 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,
confusion, restlessness, behavioral changes and lethargy. These
symptoms may develop over a few months preceding the onset of SARD.
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. However, endocrine testing (i.e., Canine
Adrenal Panel at the University of Tennessee College of Veterinary
Medicine Endocrinology Service) often shows elevations in adrenal sex
hormones. Clinical signs and disease progression vary markedly among
individual animals, depending on the number and type of hormones that
are increased, the degree of hormone elevation, and the age of the
dog. Autoimmune disease as a cause has also been called into question
because of a lack of antiretinal autoantibodies in dogs with SARD in
Diagnosis 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. 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.
Treatment Currently there is no approved treatment,
although the use of intravenous immunoglobulin has been investigated
due to similarities between SARD and human immune-mediated