These dog breeds have a higher likelihood of getting cancer, new research says

Researchers have discovered which dog breeds are more likely to get cancer, and the results disprove the notion that the largest dogs have a higher risk of the disease.

It turns out that large -- but not the largest -- dog breeds generally have the highest cancer risk, according to the study, published Tuesday in Royal Society Open Science told ABC News.

The researchers sought to understand how cancer starts, how it is initiated, and well as ask specific questions about how that inception is related to dog breeds, Leonard Nunney, an evolutionary biologist at the University of California, Riverside and lead author of the paper, told ABC News.

In humans, the pattern shows that as the body gets bigger, it is expected to be more prone to cancer, Nunney said. But this theory does not translate to man's best friend, the research shows.

"You have things that range in size from a chihuahua up to a mastiff, or a Great Dane," he said. "So there's a huge range of size."

Since big dogs typically die at a much younger age, they actually have less of a risk to develop cancer than medium-sized dogs, Lunney said.

"That's simply because they're dying younger," he added.

Some of the breeds that are most prone to getting cancer are flat-coated retrievers, Bernese mountain dogs and Westies, Lunney said.

Flat-coated retrievers typically get a type of sarcoma, a rare cancer that develops in the bones and soft tissues, at a high frequency, he added.

Most terriers, especially the Scottish terrier, have a higher likelihood to develop cancer than previously expected, given their size, Lunney said. Terriers have a higher incidence of bladder cancer, he said.

The good news is that not many breeds are excessively prone to cancer, Lunney said.

The results of the study provide insight into the number of genetic mutations that cause cancer in dogs and show that while inbreeding in the ancestry of a breed shortens its lifespan, it does not increase cancer risk in general, the researchers said.

The model used in the study can also be applied in the future to determine whether breeds are starting to get more of a particular cancer, Lunney said.

"Dogs are an extremely good model for understanding the genetic changes that may lead to a higher susceptibility of specific cancers," he said.