New Study Reveals What Determines Ear Length in Dogs

Ever see a basset hound and find yourself wanting to (gently) grab its long, floppy ears and give them a little waggle? The cute aggression caused by those droopy eared canines is real. And researchers at the University of Georgia recently found out what causes some dogs' ears to be so irresistibly appealing. Published in Scientific Reports, the study determined which DNA variants are likely responsible for the length of your pup's ears. The researchers analyzed the genetic code of more than 3,000 dogs, wolves and coyotes to find the part of the genome responsible for determining man's best friend's ear size. The present study found ear length is determined by genomic differences near the gene MSRB3, something the researchers weren't expecting. MSRB3 determines whether a dog has pointy ears like a German shepherd or droopy ones like a bloodhound. Mutations in the gene are also linked to hearing loss in people. "We only used drop-eared dogs in our study," said Leigh Anne Clark, corresponding author of the study and an associate professor in the UGA College of Veterinary Medicine. "There shouldn't have been differences at that location in the genome because they all had floppy ears." "What we learned is that there's a combination of alleles, or different DNA sequences, at this locus that dictates whether a dog has prick ears like a husky versus drop ears like a cocker spaniel. But then there is an extra allele on top of that combination that determines if the ear will be short or long." Inspired by undergraduate researcher Anna Ramey's cocker spaniel, the study is the first to pinpoint the genetic basis underlying ear size in canines. Gene selection by breeders can affect looks, health of dog Dog ears come in a variety of shapes and sizes: prick, drop, button, rose, bat. Each type has its own advantage for form, function or a combination of both. The prick ear of a Belgian Malinois, for example, helps it hear and detect the source of far-off sounds. The soft, long ears of a beagle enable it to focus on scents while somewhat blocking off outside noise. A French bulldog's bat ears are, well, mostly for looks at this point. While some of these characteristics evolved naturally, selective breeding by humans amplified these differences. Clark's lab isn't typically focused on dog phenotypes. She studies inherited diseases in dogs and their genetic underpinnings. But the new findings may still play a role when mapping other diseases in further research. "It's important for us to understand what genes and genomic regions are being selected for in breeds, especially when we're thinking about genetic disorders," says Clark. Now that the researchers know more about this particular location in the genetic code and how breeders may select for these mutations, they can account for that in future studies.