Curing Blindness in Dogs Gives Us Insight into Helping Blind Children

When Dr. Gustavo Aguirre set out to find a cure for night blindness in dogs, a disease related to Progressive Retinal Atrophy, he knew it was going to require a lot of patience. When he started studying this disease, there was no map for the canine genome. He was able to find the mutated gene that caused the disease, and, by saving his genetic samples, he made a significant contribution to the mapping of the canine genome, which was completed in 2004. 

With this information, he was able to find not just a cure, but the knowledge needed to help dog owners prevent the disease through selective breeding. The benefits of his work extend far beyond the dogs who got a second chance for sight. Read on to learn how discoveries that start with dogs can pay off for humans and other species as well.

WHY MAP THE CANINE GENOME?

It took a long time for the industry to map the canine genome, mostly because researchers weren't always convinced it was worth it. What they didn't realize was that, in some ways, dogs are very worthwhile research subjects when it comes to scientific discoveries.  Why? Because, as Erica Kitchen, director of Development & Communications for the Canine Health Foundation explains, "Purebred dogs have cleaner genetic backgrounds. Human beings are all mutts. Purebred dogs don't have the genetic noise in the background, so you can find the genetic cause of a disease more quickly than in mixed-breed dogs or humans. This speeds up the amount of time it takes to find the genetic causes of diseases in humans."

Dogs and humans have similar genetic makeups. As Kitchen puts it, "We also share the same environment, live in the same world, and drink the same water." This makes something called "comparative medicine" possible, which is the practice of working from commonalities to translate discoveries across species. A larger movement called One Health promotes comparative medicine as a way to move science forward for the benefit of humans and pets alike.

PINPOINTING THE CURE

Aguirre discovered the gene that causes congenital stationary night blindness in a breed of dogs called Briard. Once he found the mutated gene, he was able to successfully cure the blindness by attaching a non-mutated gene to a virus and injecting it into a blind dog's eye. This corrected gene "infects" the eye, restoring sight. This practice was necessary for dogs that were already blind, but won't be necessary for future generations. That's because Aguirre discovered the information needed to help breeders consciously breed night blindness out of their dogs' offspring. 

To share his discovery, Aguirre traveled with Lancelot, a dog whose sight he had restored.

A SECOND CHANCE AT SIGHT FOR HUMANS

Though there's no such thing as "selective breeding" for humans, the gene therapy Aguirre used on Lancelot is still relevant to helping ensure lifelong vision for people with a similar disease. For humans, the disease is manifested as general blindness (called Leber’s Congenital Amaurosis, or LCA), rather than night blindness. Babies born with LCA have very reduced vision. After this discovery was made for dogs, the treatment went into testing phase in the Children's Hospital of Philadelphia. So far, it's been successful.

DOG-FRIENDLY RESEARCH PRACTICES

You may be wondering whether or not these studies create any discomfort for dogs. As Kitchen explains, the CHF doesn't fund any studies that don't comply with their animal research policies, which require all the animals to be cared for and treated properly, and all researchers to be held accountable. In genetic research like this, all the testing is done by collecting DNA from blood samples. That means the dogs aren't even in a research setting; they just provide samples when they are receiving care or when their owners take them to the veterinarian. When researchers put out a call for participation, all blood samples are provided voluntarily, with the consent of the dog's owner.

"We have DNA banks where owners can submit samples for studies that haven't even been thought up yet," Kitchen explains. "So in that particular case that's really easy on the dog. They're not really in the research setting."

SHARING THE KNOWLEDGE

Once a discovery has been made, it sends ripples through the whole research industry. CHF hopes that this breakthrough will focus interest on the ways that the study of the canine genome can improve life for pets and people alike.

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