Big dog, little dog

2007-04-06 14:08

Washington - From the towering Great Dane to the feisty little Chihuahua, all dogs are brothers under the skin. Now, researchers have uncovered a clue to why the animals wearing that skin vary so much in size.

Dogs have the largest variation in body size of any land animal, so researchers led by Elaine A. Ostrander of the National Human Genome Research Institute decided to look into the reasons why.

Their finding of a section of genes that controls small size in dogs is reported in Friday's issue of the journal Science.

Learning how growth is controlled can improve the understanding of cancer and other diseases caused by growth gone awry, Ostrander explained in a telephone interview.

And the research adds to the basic study of variations, perhaps improving knowledge of the differences between people, she added.

Disease a common thread among humans and dogs

K Gordon Lark of the University of Utah, a co-author of the report, pointed out that dogs have 200 to 300 diseases in common with people, including high blood pressure, autoimmune diseases and cancer.

"They also share our environment, so if there is an environmental influence that can trigger disease," dogs will be going through the same process, he said in a telephone interview.

"So, if we can solve this in dogs, that's a fantastic jump ahead," Lark said.

Keith E Murphy, principal investigator at the Canine Genetics Laboratory of Texas A&M University, called the research "an incredible piece of work."

It was suspected that there might be a few major genes controlling significant differences in body type, Murphy said.

"What you've got here is the first piece of that puzzle. That's very important, and you're looking at almost a sort of cascade effect, if you will, and we would hope that these findings, maybe you can extend to diseases... maybe even cancer," said Murphy, who was not part of the research team.

"The dog and the human are almost walking in lock step. The study of the human benefits the dog, and study of the dog benefits the human," he said.

- AP