Over the years I’ve developed a top ten list of my most despised diseases. Those that make it to this list tend to be diseases that are untreatable, leaving me helpless to help my patient. Such is the case with Sudden Acquired Retinal Degeneration Syndrome (aka, SARDS). In addition to being untreatable, the cause of SARDS is unknown. (Note to reader: the less that is known about a disease, the longer the name of that disease.)
What we do know about SARDS
SARDS is a disease of middle age, and approximately 60% of affected dogs are females. Any breed is susceptible, but Dachshunds, Miniature Schnauzers, Pugs, Brittany Spaniels, Malteses, Bichon Frises, and mixed-breed dogs are particularly predisposed.
SARDS affects the retinas which receive visual input and then transport this information to the brain via the optic nerve. In dogs with SARDS, the photoreceptors (rods and cones) and possibly the nerve fiber layer within the thin-layered retinas undergo degenerative changes. The end result is complete blindness. These changes are microscopic in nature- one cannot detect them by performing a basic eye exam. The diagnosis of SARDS is made based on the patient’s history, the presence of partial to complete blindness in both eyes, normal appearing retinas, and characteristic changes on an electroretinogram (ERG). The ERG is a test used to evaluate photoreceptor function and is performed by veterinarians who are specialists in ophthalmology.
It’s been theorized that SARDS is an autoimmune disease in which a misbehaving immune system attacks the body’s own normal cells. Dogs with SARDS who have received immunosuppressive therapy (the treatment of choice for autoimmune diseases) have not demonstrated any clear improvement in overall outcome compared to untreated dogs.
All dogs with SARDS develop complete and permanent blindness over a rapid course, typically days to weeks. Stumbling, difficulty navigating at night, and failure to track treats are the most commonly reported early symptoms of visual impairment.
During the weeks to months preceding their blindness, most SARDS-affected dogs also experience marked increases in appetite and/or thirst with subsequent weight gain and changes in urinary behavior. Testing for hormonal imbalances (diabetes mellitus, Cushing’s Disease) that classically cause these symptoms is commonly pursued and typically comes up empty. Savvy veterinarians consider the possibility of SARDS before loss of vision becomes apparent. In most cases, it is not until vision wanes that the diagnosis of SARDS becomes suspect.
Long-term outcomes for affected dogs and their human companions
When a dog develops SARDS, a significant period of adjustment is required for everyone involved. Imagine living with a newly blind dog who is begging for food, drinking incessantly, and urinating copious amounts (all that water has to go somewhere).
A study of long-term outcomes in dogs with SARDS surveyed 100 people living with SARDS-affected dogs. In addition to blindness, most of the dogs were reported to have increased thirst, urine output, and appetite along with weight gain. Increased appetite was the only one of these symptoms reported to increase over the course of one year following the SARDS diagnosis.
In this study, 22 of the 100 dogs received some sort of treatment (corticosteroids, nutritional supplements, melatonin, and/or doxycycline) for their blindness. None experienced improved vision in response to therapy.
Eighty-seven percent of the dogs were reported to have moderate to excellent navigation skills within their home environments, and 81% had moderate to excellent navigation skills within their yard environments. Of the people surveyed, 48% reported making special provisions for their dogs such as the use of baby gates, fencing, and ramps, carpeting pathways to important locations, and auditory clues or scents to signify certain locations.
Thirty-seven percent of respondents reported that the relationship with their dog actually improved after the SARDS diagnosis. The authors of the study theorized that the increased time and involvement necessary to care for a blind dog may have been responsible for enhancing the human-animal connection. Only 17% reported that the relationship with their dog worsened.
Seventy-six percent of respondents ranked the quality of their dog’s life to be moderate to excellent. Only nine dogs were reported to have a poor quality of life. Of the 100 people surveyed, 95 indicated that they would discourage euthanasia if advising others caring for dogs with SARDS. One must bear in mind that those who chose to euthanize when SARDS was diagnosed were not surveyed.
This study provides truly uplifting results. While adaptation to a dog’s loss of vision usually proceeds smoothly, when one factors in the other SARDS symptoms that accompany the blindness, the challenge to maintain quality of life for everyone involved increases significantly. Dogs and the people who love them can be amazingly adaptive creatures!
Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet