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Tag: selective breeding

Without some diversity, English bulldogs could become a breed of the past

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Due to centuries of selective breeding, and the efforts of breeders to keep the breed “pure,” the English bulldog has become so inbred it cannot be returned to health without an infusion of new bloodlines, a genetic study says.

The study, appearing in the journal Canine Genetics and Epidemiology, reached the stark conclusion that health issues created by human manipulation of the breed could lead to its doom.

“We tried not to be judgmental in our paper. We just said there’s a problem here, and if you are going to decide to do something about it, this is what you’ve got to work with, said co-author Niels Pedersen of the University of California, Davis.

“If you want to re-build the breed, these are the building blocks you have, but they’re very few. So if you’re using the same old bricks, you’re not going to be able to build a new house.” told the BBC.

Pedersen and colleagues from the Center for Companion Animal Health at UC Davis examined the DNA of 102 registered English Bulldogs and found an alarmingly low level of diversity.

That, they say, is the result of a small initial pool of founding dogs, and “bottlenecks” caused by breeding for “desirable” traits like a big head and a short snout.

Those traits have led to many of the breed’s health problems — difficulty breathing, poor mobility and reproductive issues among them.

The researchers say efforts to return the breed to health by using existing bloodlines alone are “questionable.”

Introducing new bloodlines, from outside the breed, are likely the only solution, but many breeders are resistant to that idea.

“The fastest way to get genetic diversity is to outcross to a breed that looks similar but is genetically distinct… Trying to manipulate diversity from within a breed if it doesn’t have much anyway is really very difficult,” Pedersen said. “If all your dogs are highly related to one another, which ones are you going to pick?”

One possibility suggested by the researchers is the Olde English Bulldogge, a 1970s attempt by an American breeder to recreate the healthier working bulldog that existed in England during the early 1800s.

“The English bulldog has reached the point where popularity can no longer excuse the health problems that the average bulldog endures,” Pedersen said in a statement.

The features of today’s English bulldog are the result of hundreds of years of breeding, but changes to the breed’s traits — flatter face, shorter nose, stubbier legs, more skin folds — have become particularly rapid in recent decades, Pedersen said.

How the sharpei got its wrinkles

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How did the sharpei get its wrinkles?

Scientists who have analyzed the genetics of 10 dog breeds say they’ve found the answer — and a path to many more.

While five genes have already been pinpointed as being responsible for dogs’ coats, leg size and more, the new research identifies 155 distinct locations in the animals’ genetic code that could play a role in giving breeds their distinctive appearances.

In the sharpei, the team found differences in a gene known as HAS2 which makes an enzyme known to be important in the production of skin.

“There was probably a mutation that arose in that gene that led to a really wrinkly puppy and a breeder said, ‘hey, that looks interesting, I’m going to try to selectively breed this trait and make more of these dogs’,” explained Joshua Akey from the Department of Genome Sciences at the University of Washington, told the BBC.

Akey and colleagues studied 32 wrinkled and 18 smooth-coated sharpeis and compared a specific stretch of their DNA with that of other breeds.

The team found four small, but significant, differences in the genetics of the two skin types of the sharpei versus the other breeds. These single nucleotide polymorphisms (SNPs), as they are called, were located in the HAS2 gene.

The research has also identified other locations in the dog genome that can now be investigated further to understand better why pedigree animals look the way they do.

Akey and his colleagues reported their findings in the Proceedings of the National Academy of Sciences.