Dogs are our partners, our protectors, and our closest companions, shaped over thousands of years by shared work and shared lives with humans. But the same human influence that built this incredible bond has also reshaped dogs in ways we rarely consider. As selective breeding intensified and certain looks or traits became fashionable, many breeds began to inherit more than just appearance—they also inherited hidden genetic weaknesses. Today, some of the very traits that define our favorite breeds carry the seeds of serious disease.
Genetic Diseases
While kennel clubs have played a major role in organizing and maintaining the more than 300 dog breeds recognized today, they have also—unintentionally—cemented certain harmful traits into breed standards. Most traits sought by breeders are ultimately controlled by genes, and when selecting for features such as coat pattern, size, or head shape, breeders have often carried genetic diseases along for the ride. Some of these conditions have become so intertwined with a breed’s identity that reversing them now poses a major challenge.
Rhodesian Ridgeback
The Rhodesian Ridgeback originated in Southern Africa during European colonization. Danish colonists brought European dogs and crossbred them with local canines, creating the earliest ancestors of the modern Ridgeback. A member of the hound group, the breed was prized for hunting ability and received official kennel club recognition in 1955. Today, it ranks as the 40th most popular breed.
The hallmark of the Ridgeback is the patch of backward-growing hair along its spine, accompanied by two symmetrical whorls, or “crowns,” near the shoulders. Breed standards are strict: a dog without a perfect ridge and matching crowns can be disqualified. This intense focus on ridge perfection has created strong selective pressure, and with it, a rise in a serious genetic defect.
A dermoid sinus is a tube-like structure that forms beneath the skin when the embryonic layers that become the skin fail to fully separate from the developing nervous system. In severe cases, this tube can extend to the dura mater—the protective layer surrounding the spinal cord—leaving the nervous system vulnerable to infection. Surgical treatment is difficult, and the prognosis can be poor. Dermoid sinuses occur far more frequently in Ridgebacks, affecting an estimated 2.5–5% of puppies.
However, some studies suggest that the genes controlling the ridge may be separate from those that cause dermoid sinuses. If this is true, breed clubs could prioritize eliminating dermoid sinus carriers while still preserving the ridge. Updating the breed standard to disqualify dermoid sinus—while easing the rigid expectations for crown placement—could help safeguard the genetic future of the breed.
Cavalier King Charles Spaniel
The Cavalier King Charles Spaniel is a small toy breed with royal roots dating back to the 16th and 17th centuries in England. These early “toy spaniels” were prized for their affectionate nature and elegant appearance, frequently appearing in royal portraits. By the 19th century the breed had nearly disappeared, overshadowed by newer toy breeds. In the 1920s, breeders sought to recreate the longer-nosed spaniels seen in paintings from King Charles II’s era, ultimately developing the modern Cavalier. The American Kennel Club recognized the breed in 1995, and it now ranks as the 13th most popular dog in the United States.
Despite their charm, Cavaliers face a severe genetic challenge. Decades of selective breeding within a narrow gene pool have left many Cavaliers with skulls too small to comfortably fit their brains. This leads to Chiari-like malformation (CLM)—and one study suggests that around 95% of Cavaliers show evidence of it.
CLM can block the normal flow of spinal fluid, leading to pockets of fluid in the brain or spine. This condition, called syringomyelia, may affect up to 50% of Cavaliers. The damage it causes is permanent. Surgery to relieve CLM is highly invasive and does not guarantee lasting relief. Dogs with syringomyelia may scratch persistently at their neck or the air, show sensitivity near the back of the skull, or display signs of chronic pain.
Because syringomyelia tends to worsen with each generation, ethical breeders must rigorously monitor their lines and remove severely affected dogs from breeding programs if the breed is to have a healthy future.
Golden Retrievers
Often considered America’s favorite dog, the Golden Retriever embodies the ideal companion: playful, intelligent, gentle, and endlessly loyal. First developed during the Victorian era for retrieving waterfowl, Goldens spread quickly across the globe for both their skill and their temperament. They joined the American Kennel Club in 1925 and today rank as the 3rd most popular breed. Michigan State University estimates there are roughly 500,000 Golden Retrievers in the United States, with around 50,000 newly registered each year.
But this popularity has come with a cost. Studies show that about 65% of Golden Retrievers die from cancer, with an average lifespan of only about nine years. Interestingly, the remaining 35% that die of other causes often die even younger, suggesting cancer is not the only genetic pressure affecting longevity.
The breed’s widespread appeal led to large-scale, rapid breeding, sometimes with more emphasis on quantity than genetic quality. Many cancer-related genes have now been identified in Goldens, and genetic testing could help responsible breeders reduce the prevalence of these mutations and improve the breed’s long-term health.
Our Best Friend Needs Our Help
Dogs have stood beside us since before the dawn of civilization. Without them, it’s uncertain whether humans would have survived the Ice Age at all. Over countless generations we have shaped dogs into companions, guardians, workers, and friends. Yet these remarkable achievements have come with unintended consequences. Some breeds are now so burdened with genetic disease that their future stability is at risk.
But these problems are not beyond repair. With the same dedication, ingenuity, and care that shaped dogs into the incredible partners they are, we can reshape their future. Genetic testing, updated breed standards, and responsible breeding practices can help ensure that our best friend remains healthy, strong, and by our side for generations to come.
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