Cavalier King Charles Spaniels carry more disease-causing gene mutations than other dog breeds. Extreme ideals of beauty in breeding led to health problems.
Uppsala – fluffy floppy ears, loyal look – and a special predisposition for genetic diseases:
According to a study by the University of Uppsala (Sweden), Cavalier King Charles Spaniels carry more disease-causing gene mutations than other dog breeds and thus have an increased risk of a certain heart disease, for example. In the journal “PLOS Genetics”, the scientists attribute this to the breeding history of the animals.
In fact, the past 300 years of controlled breeding have not only produced a wide variety of dog breeds: in some cases, increasingly extreme ideals of beauty have led to massive health problems. A well-known example is the pug, which should appear particularly flat-nosed and puffy-eyed for a long time. As a result, many pugs suffer from breathing and corneal problems, and some specimens can even have an eye falling out.
In the case of other breeds, the breeding sequences are not directly apparent. In many cases, however, inbreeding has led to an increasing number of genetic diseases that they inherit. A research group led by the Swedish evolutionary geneticist Erik Axelsson has now investigated precisely this connection between breeding practices and genetic heritage. The scientists sequenced the genome of 20 dogs of eight common breeds, including beagles, German shepherds and golden retrievers.
Always short-nosed and round-headed to look particularly cute
The result: The number of disease-causing gene variants was higher in the Cavalier King Charles Spaniel than in the other breeds examined. Among other things, the breed is susceptible to so-called myxomatous mitral valve disease, a form of heart failure in dogs. The study authors attribute this to the breed’s intense and long history, which probably goes back at least a thousand years.
Written mentions can be found in 500 year old records from Great Britain. The small spaniels are the direct descendants of the dogs of the British aristocracy, King Charles I (1600-1649) even had his four-legged friends immortalized in a painting next to his children. In the centuries that followed, the animals were bred to be short-nosed and round-headed through crossbreeding with breeds such as the pug, in order to look particularly cute.
That changed in the 1920s. At that time, the US American Roswell Eldridge, who lived in London, went in search of specimens that were closer to the long-nosed spaniel of the old type, as can be seen in historical pictures. Eldridge called for an annual competition, the most famous and multiple winner of which was the male “Ann’s Son”. The animal is considered to be the progenitor of the breed that was revived in this way.
Overall, according to the authors of the current study, there have always been bottlenecks in the breeding history of spaniels in which only a small percentage of the population has passed its genes on to the next generation. Those shortages may have caused the harmful genes to appear more abundantly in the Cavalier King Charles Spaniel’s genome before the dog was finally recognized as a breed in 1945. dpa