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Sudden Acquired Retinal Degeneration Syndrome (SARDS) in Dogs

Posted September 25, 2014 in Dog Diseases & Conditions A-Z

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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)
  • Stumbling
  • 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

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Nancy has more than 30 years of experience in the veterinary industry and is a board-certified veterinary specialist in internal medicine as well as a valued member of IDEXX’s Pet Health Network team since 2014.