Share it! Science : Man's Best Friend May be the Key to Understanding Blindness

The anatomical structure of the human eye is very similar to that of a dog's eye. Therefore, learning about issues in the eyes of dogs might shed light on understanding similar problems in human eyes. In an international effort that spanned the course of a decade, scientists from Sweden, Finland and the United States teamed up to understand a type of retinal disease found in Swedish vallhund dogs.

Swedish vallhund (photo: TS Eriksson via Wikimedia Commons)

The Swedish vallhund is a fairly rare breed that almost became extinct in the 1940's. These pups have been used for hundreds of years as a herding dog. Despite the dog's short, Corgi-like legs, and diminutive appearance, they are active and effective work dogs.

Scientists recently identified the underlying issue causing progressive retinal atrophy (PRA), ultimately blindness, in these dogs. The blindness is caused to a gene defect on the MERTK gene. This gene defect is associated with one of the most common forms of human blindness throughout the world, a type of human retinitis pigmentosa (RP). This type of human RP is currently incurable, so learning more about the gene defect in eyes that are similar to our own, like those in these dogs, could serve very useful in developing potential human treatments.

This research began when scientists from the University of Helsinki discovered some abnormalities in the eyes of Swedish vallhunds in the 1990s. In 2004, the same problems were brought to the attention of a researcher at the University of Michigan and an international collaboration of scientists began shortly after. With a strong team of researchers, this group has been able to not only identify a new disease and the genetics behind it, but has also investigated glaucoma in the Norwegian Elkhound. They were able to develop genetic testing related to glaucoma to help breeders prevent it. Plans for future studies include learning about possibilities of a MTERK inhibitor that could serve as a therapy for this type of blindness in the Swedish vallhund. Although it will take time, these studies could give way to important information on how to prevent blindness caused by human RP.

Several studies have been completed on dogs that may have direct impact on understanding the health of humans. In 2010, work with Staffordshire terriers linked genes for a rare and fatal neurodegenerative disease in humans and the dogs. In 2011, researchers found that genetic mutations in Tibetan terriers was also found in a fatal human disorder related to Parkinson's disease. In 2013, studies of the Dandie Dinmont terrier began to pave the way to understanding the gene behind a certain type of glaucoma associated with human glaucoma. These are just a few examples of how learning about one of our favorite types of animals could mean dogs truly are man's best friend!

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