What causes sudden blindness in dogs?
Sudden blindness. Eating more than normal. Increased thirst. Frequent urination. Doesn’t want to go for walks anymore. History of recent weight gain.
I’m losing count of how many times I’ve read this same list of clinical signs in a canine patient’s file as I search through electronic medical records at the Western College of Veterinary Medicine (WCVM).
My research supervisor, veterinary ophthalmologist Dr. Lynne Sandmeyer, has asked me to identify all of the dogs diagnosed with a condition called sudden acquired retinal degeneration syndrome (SARDS) at the college’s Veterinary Medical Centre (VMC) over the past 20 years. SARDS is a condition that causes dogs to suddenly and permanently go blind because their retinas degenerate. Small breeds like dachshunds, miniature schnauzers and pugs are most often diagnosed, but any breed of any size can be affected. The exact cause of SARDS is unknown, and unfortunately, there is no treatment available.
My goal is to gain a better understanding of SARDS by comparing as many affected dogs as possible. Did they all have the same abnormality in their blood work? Did they have previous or concurrent eye problems? Did they all act the same before they went blind?
These are just some of the questions I’m trying to answer as I search through the medical records. My goal is to try and help find out what causes the disease or even find something that could treat the condition and improve the quality of life for dogs living with SARDS.
A true diagnosis of SARDS requires an advanced test called an electroretinogram (ERG) that tests whether or not the retina is working properly. An ERG is only available at a referral centre like the VMC where ophthalmologists diagnose about one dog every month with this blinding condition.
However, the number of dogs affected by SARDS is likely much higher since not every dog affected with sudden blindness is referred to the college’s VMC for specialized testing.
As if the blindness wasn’t enough, SARDS-affected dogs can also show clinical signs of increased thirst, appetite and urination as well as weight gain. These signs are commonly seen with a different disease called hyperadrenocorticism (Cushing’s disease).
Researchers are still trying to understand the relationship between SARDS and Cushing’s disease. The clinical signs of increased thirst, urination and appetite can show up before, during or after blindness in SARDS patients — yet they often disappear over time.
A SARDS diagnosis is not something to be taken lightly. In addition to the troubling clinical signs, the permanent blindness associated with SARDS requires major adjustments for both dog and owner.
Similar to a blind person learning to use a cane and read braille, a blind dog must learn new commands. It also relies much more on smell and hearing to successfully navigate its environment. A blind dog requires more care and supervision than a seeing dog, and owners often find themselves in the position of being the seeing-eye-human for their blind dog.
The challenge of living with a blind dog is something Twyla Budz knows all too well. Her dachshund, Max, was diagnosed with SARDS in 2014 and lived with the condition until he passed away in 2016.
Twyla recalls how living with Max after he became blind was “no different than a mom with a little baby.” She had to learn to understand his different ways of communicating and help him adjust to his new reality.
One of the most difficult parts for her was finding new things for Max to enjoy when he could no longer do some of his favourite things, such as sitting by the window to watch deer and rabbits play in the front yard.
Twyla’s determination paid off, and she and Max grew closer than ever as they learned to enjoy new activities together. Despite his blindness, Max learned to play in the yard again, and he liked to chase water that Twyla sprayed on the grass with a garden hose.
What advice does Twyla give to owners of dogs that have been recently diagnosed with SARDS?
“As long as you’re patient and they know that you’re always there for them … and you show them that there’s nothing to fear, they live absolutely fine.”
Twyla’s greatest hope is that in 10 to 15 years, veterinarians will be able recognize the clinical signs of SARDS early enough to diagnose and treat the disease before affected dogs become blind.
I hope so, too. Hearing Twyla and Max’s story reminds me that there’s always a way to solve a problem as long as you keep looking for answers.
So that’s what I do – one file at a time.
Danica Lucyshyn of Saskatoon, Sask., is a third-year veterinary student who was part of the Western College of Veterinary Medicine’s Undergraduate Summer Research and Leadership program in 2016. Danica’s story is part of a series of stories written by WCVM summer research students.