What Causes Sudden Blindness in Older Dogs?
Many dog owners have experienced blindness in their dogs associated with various diseases. Cataracts and blindness are an inevitable result of diabetes in dogs. Kidney failure and resulting hypertension can result in retinal detachment and blindness. A less known cause of sudden blindness in dogs is Sudden Acquired Retinal Degeneration Syndrome, or SARDS.
Dogs Affected by SARDS
SARDS is most often diagnosed in older animals. The median age for the condition is 8.5 years. Dachshunds and Miniature Schnauzers are particularly afflicted. Pugs, Brittany Spaniels, and Maltese are other breeds that show a predisposition for the condition. Sixty to seventy percent of the dogs with the condition are female. Interestingly, one study found that 46 percent of SARDS cases were diagnosed in the holiday months of December and January.
Cause of SARDS in Dogs
The cause and retinal changes of SARDS are unknown and poorly understood. The cells of the rods and cones of the retina suddenly undergo programed cell death or apoptosis. Inflammatory, autoimmune, or allergic causes, although suspected, have not been confirmed. The lack of inflammation associated with the condition and the poor response to treatment as an immune related disease suggest a non-immune related cause.
Symptoms of SARDS in Dogs
Prior to blindness, many dogs will show navigation difficulty around the house and yard. They may bump into things or show caution in movement. Blindness is considered permanent, although some owners of younger dogs stricken with the condition report intermittent sight. Because blind dogs quickly accommodate to vision loss, these observations may not reflect actual recurrence of vision.
Forty to fifty percent of dogs with SARDS also have increased water consumption, increased urination, increased food consumption, and weight gain. These symptoms persist after the onset of blindness, especially the change in food consumption. Because these are the same symptoms associated with a hormonal condition called hyperadrenocorticism, or Cushing’s disease, a link with SARDS was speculated. Actually, studies indicate that few SARDS patients have Cushing’s.
Living With a Dog Affected With SARDS
A recent survey of owners of dogs affected with SARDS indicates that owners perceive the quality of their dogs' life as good. Of the 100 dogs represented in the survey, only nine owners reported that they thought their dogs' quality of life was poor. Owners also reported that navigation abilities in both the house and the yard were moderate to excellent. Forty percent of owners reported moderate to excellent navigation even in new and unfamiliar surroundings.
Forty-eight percent of the owners found no need to make special provisions for their blind dogs. Despite the decrease in play, increase in sleep, and other signs of depression, few owners found that their relationship with their dogs changed with SARDS. In fact 40 percent indicated that their relationship was improved, with most indicating a profound improvement with the relationship.
Although 62 percent of owners in the survey felt that blindness was the most important factor in decreased quality of life, few thought that euthanasia was appropriate. In fact 95 percent of owners indicated that they would discourage euthanasia for dogs with SARDS. This included five owners who did euthanize their dogs due to SARDS but in retrospect felt that it was unnecessary. Interestingly, of the five owners indicating that euthanasia was the best choice for SARDS patients, only two of them actually euthanized their dogs.
SARDS is a frustrating condition. Without a cause we have no way of knowing how to prevent it or how to treat it to stop the progression of the disease. Although blindness is certainly a sad condition for dogs and owners, these dogs can continue to have a good quality life.
Dr. Ken Tudor