Sudden acquired retinal degeneration or SARD’s is characterized by sudden loss of vision. Clinical examination of the eye soon after onset is normal. This syndrome has been called “toxic neuroretinopathy”, “metabolic toxic retinopathy”, and “silent retina syndrome”. SARD patients usually appear in good health, but in some instances there is recent history of obesity, increased urination and increased appetite and water consumption. Some SARD’s patients show signs suggesting hyperadrenocorticism (Cushing’s Syndrome), while others show signs of subclinical liver disease. SARDS has been identified in many breeds, and is more common in middle-aged dogs.
Typically, there is no response to visual stimuli in SARDS patents. Definitive diagnosis is made with an electroretinogram (ERG). The ERG can differentiate SARDS patients from other causes of blindness such as optic neuritis or a brain lesion. Although there are no clinical visual lesions at first, after several weeks or months, ophthalmoscopic evidence of generalized retinal degeneration becomes apparent. Electron microscopy studies revealed that SARD is characterized by rapid loss of photoreceptors outer segments, both rods and cones, followed by degeneration of other retinal layers. Different regions of the retina are affected equally. Aggressive research is ongoing to find a cause and cure for this devastating retinal disease.