Sudden acquired retinal degeneration syndrome (SARDS) is characterized by very rapid vision loss in adult dogs. It causes rapid destruction of the rods and cones (photoreceptors) of the retina leading to blindness. The cause for this destruction is currently unknown, and is the subject of significant, on-going research. Affected dogs are typically middle aged to older, and all breeds can be affected. There is no evidence to suggest that this disease is hereditary and there is not any known means of preventing the condition. Most dogs will go completely blind within four weeks of the noticeable onset of vision loss, and many dogs will have total vision loss within 1 -2 weeks. Owners often report increased thirst and appetite, and weight gain coinciding with the vision loss. As these signs may be indicative of an endocrine or hormonal dysfunction, diagnostic testing will be recommended to assess for any systemic disease.
In any patient where vision is lost, a complete ophthalmic exam is essential. Your ophthalmologist will examine the front and back of the eye with several instruments. When blindness has recently occurred and is due to SARDS, the exam is often completely normal.
To determine if the patient’s vision loss is due to retinal degeneration or a brain lesion, an electroretinogram will be recommended. This test measures the electrical signals generated by the photoreceptors in the eye in response to light. If normal electrical signals are present, it tells us that the retina is working and that the loss of vision is due to a brain problem. If there are minimal to no electrical signals from the eye then it tells us that the loss of vision is due to sudden acquired retinal degeneration. Should the electrical signals be present yet significant diminished, an auto-immune condition of the retina, immune-mediated retinitis (IMR), may be the cause for the vision loss and respond to intensive medical therapy. The visual prognosis for IMR is typically poor, however despite early detection and medical intervention.
As the underlying cause for SARDS has yet not understood, unfortunately there is no effective treatment or prevention for SARDS. The blindness is irreversible. The accompanying symptoms of weight gain, increased appetite, and increased thirst typically subside over the course of several months.
It is important to understand that SARDS is not a painful condition. Most all pets with blindness maintain a good quality of life. Some dogs with SARDS are initially anxious and unpredictable, probably because of the exceptional stress of sudden vision loss. However, most dogs will eventually adjust to their blindness and their other senses seem to become more heightened over time. It is key to keep the home environment as stable and familiar as possible. Food and water bowls, furniture and everyday objects should be kept in consistent locations. Pets should be restricted from pools and balconies and not be left outside unsupervised. Dogs that enjoy toys generally continue to play with toys that make sounds or whistles and balls containing bells. It is vital to keep blind dogs active and involved in life. Fortunately, most dogs do not experience long lasting depression following vision. After-all, they have you to look after them! Some dogs adapt quickly, while others adapt over a few months. Occasionally, pets with SARDS develop cataracts months to years following diagnosis. An annual eye examination is recommended to monitor for signs of cataracts. Provided they remain small, anti-inflammatory therapy for the cataracts is not needed.