Over the years I’ve developed a top ten list of my most despised diseases. Those that make this list tend to be diseases that are untreatable, leaving me helpless to fix 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 in dogs
SARDS is a middle age disease in dogs, 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 thin-layered 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 layers within the 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. Therefore, 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. However, 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.
Symptoms of SARDS in dogs
All dogs with SARDS develop:
- Complete and permanent blindness over a rapid course (typically days to weeks)
- Difficulty navigating at night
- A failure to track treats
During the weeks and 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.
Diagnosing SARDS in dogs
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 SARDS 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 of that water has to go somewhere).
A study, published in the Journal of the American Veterinary Medical Association, 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, 28% 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.
This study provides truly uplifting results. While adaptation to a dog’s loss of vision usually proceeds smoothly, factor in the other SARDS symptoms and the challenge to maintain quality of life for everyone involved increases significantly. Dogs and the people who love them can be amazingly adaptive creatures!
Questions to ask your veterinarian:
- What can I do to help my dog adapt to his blindness?
- What are some tips for keeping my dog safe now that he is blind?
- How will I be able to know if my dog’s quality of life remains good?
- Can we stay in communication to discuss symptoms over the next few months?
If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.
Thursday, September 25, 2014
SARDS is typically diagnosed on the basis of a thorough eye exam. Your veterinarian will perform a number of tests to assess your dog’s vision and visual reflexes. The pupils will not respond normally to light and your dog will show a number of other responses consistent with blindness.
The only way to definitively diagnose SARDS is with a test called electroretinography (ERG).
This test involves flashing a bright light in front of the eye and monitoring the electrical activity of the retina. If there is no electrical activity within the retina (a ’flat line’), the dog can be definitively diagnosed with SARDS. However, this test is rarely performed because it requires referral to a veterinary ophthalmologist. Therefore, most cases of SARDS are diagnosed on the basis of history and clinical signs on veterinary exam.
Your veterinarian may perform blood tests, including a complete blood cell count and serum biochemistries. While there are typically no bloodwork changes seen with SARDS, this bloodwork can help rule out other conditions that may cause blindness. Given the correlation between SARDS and Cushing’s disease, your veterinarian may also recommend a test for Cushing’s disease.
Sudden Acquired Retinal Degeneration Syndrome (SARDS) in Dogs - pets
SUDDEN ACQUIRED RETINAL DEGENERATION SYNDROME
Sudden acquired retinal degeneration syndrome (SARDS) is a retinal disorder of unknown cause that results in an acute onset of permanent blindness in adult dogs. 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. There is no proven treatment available for this condition.
The primary complaint is always acute vision loss. 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 one to two weeks. Some owners notice the first signs in poor lighting conditions.
Though many dogs have no clinical signs of illness other than blindness, some dogs will show signs typical for Cushing's disease (increased thirst, increased urination, weight gain) though they usually test negative for Cushing's disease. These other signs commonly resolve over time.
An electroretinogram will likely be recommended for your pet in order to evaluate retinal function. This test will confirm or rule-out the diagnosis of SARDS by quantifying how much, if any, retinal function is present.
Some dogs afflicted with SARDS become very anxious and unpredictable, probably due to the exceptional stress of sudden vision loss. However, most dogs will eventually adjust to their blindness and their other senses seem to become more sensitive over time. It is important to keep the home environment as stable as possible and objects should be kept in consistent locations. Pets should not be left outside unattended unless they are in a confined space such as a yard.
Sudden Acquired Retinal Degeneration Syndrome (SARDS)
Sudden Acquired Retinal Degeneration Syndrome or SARDS is a disease which leads to sudden and irreversible blindness. At the time of writing the disease has only been seen in dogs. The condition affects the retina, which is the structure at the back of the eye that functions like the film in a camera. Without retinal function the affected animal cannot see. In the early stages of the condition the retina looks normal, even though it is no longer working.
Objective: To investigate long-term outcomes and owner-perceived quality of life associated with sudden acquired retinal degeneration syndrome (SARDS) in dogs.
Animals: 100 dogs with SARDS examined at 5 academic veterinary institutions from 2005 to 2010.
Procedures: The diagnosis was based on documented acute vision loss, normal results of ophthalmic examinations, and evaluation of extinguished bright-flash electroretinograms. Primary owners of affected dogs completed a questionnaire addressing outcome measures including vision, systemic signs, and perceived quality of life for their dogs.
Results: Age at diagnosis was significantly correlated with positive outcome measures dogs in which SARDS was diagnosed at a younger age were more likely to have alleged partial vision and higher owner-perceived quality of life. Polyphagia was the only associated systemic sign found to increase in severity over time. Medical treatment was attempted in 22% of dogs visual improvement was not detected in any. Thirty-seven percent of respondents reported an improved relationship with their dog after diagnosis, and 95% indicated they would discourage euthanasia of dogs with SARDS.
Conclusions and clinical relevance: Blindness and concurrent systemic signs associated with SARDS appeared to persist indefinitely, but only polyphagia increased in severity over time. Most owners believed their pets had good quality of life and would discourage euthanasia of dogs with SARDS.