Larger dogs may not necessarily be more susceptible to cancer.
Researchers have discovered which breeds of dogs are most susceptible to cancer, and the results disprove the idea that larger dogs have a greater risk of developing the disease.
It turns out that large — but not the largest — dog breeds generally have the highest risk of cancer, according to the study published Tuesday in the journal Royal Society Open Science He told ABC News.
The researchers sought to understand how cancer begins, and how it begins, as well as ask specific questions about how this genesis relates to dog breeds, Leonard Nooney, an evolutionary biologist at the University of California, Riverside and lead author on the paper, told ABC News.
In humans, the pattern shows that the larger the body, the more likely it is to develop cancer, Nooney said. But research shows that this theory does not translate to man's best friend.
“You have things that range in size from a Chihuahua to a Mastiff, or a Great Dane,” he said. “So there's a huge range of size.”
Since large dogs typically die at a much younger age, they are actually less likely to develop cancer than medium-sized dogs, Looney said.
“This is simply because they die at a younger age,” he added.
Some of the breeds most at risk for cancer are flatback retrievers, Bernese mountain dogs and Westies, Looney said.
He added that flat retrievers typically develop a type of sarcoma, a rare cancer that develops in bones and soft tissue with a high frequency.
Most terriers, especially Scottish terriers, have a higher likelihood of developing cancer than previously thought, given their size, Looney said. He said terriers have a higher incidence of bladder cancer.
The good news is that there are not many breeds that are overly susceptible to cancer, Looney said.
The researchers said the study results provide insight into the number of genetic mutations that cause cancer in dogs, and show that although inbreeding in a breed shortens its lifespan, it does not increase the risk of cancer overall.
Looney said the model used in the study could also be applied in the future to determine whether strains are starting to become more susceptible to a particular cancer.
“Dogs are a very good model for understanding genetic changes that may lead to increased susceptibility to certain cancers,” he said.
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