When it comes to the life span of dogs, researchers have found that size matters: Small dogs live longer than large dogs.
“Smaller breeds like Chihuahuas can live more than twice as long as the giant Great Dane,” said Matt Kaeberlein, a molecular biologist at the University of Washington in Seattle. “That is about 56% of the variation in life span.
“It is not just a purebred problem — the relationship between size and life span is just as strong in mixed-breed dogs.”
When looking at the average life spans of dogs based on breed, life spans may vary due to health issues associated with a specific breed.
We all know that elephants live longer than mice. So, what is going with our dogs?
When our pals are 1 year old, they are about the age of a 15-year-old person. The second year in a dog’s life compares to about another nine years for us.
Aging Process
After that, the aging process in dogs varies based on their size and age.
“The oldest known Chihuahua on record, named Megabyte, passed away at 20 years and 265 days old,” according to Dr. Jessica Seid, a veterinarian representing Hill’s Pet Nutrition.
The Guinness World Record for the longest-living dog is a medium breed dog born in Australia in 1910, an Australian Cattle Dog named Bluey, who lived for 29 years and 5 months.
It’s not uncommon for some giant breeds such as Great Danes and Mastiffs to gain upward of a hundred pounds in the first 1½ years of life, whereas some small breeds such as Chihuahuas and Yorkshire Terriers may only gain 10 pounds or less in their first 1½ years of life.
Numerous scientists believe that smaller dogs live longer because they grow more slowly than large breed dogs. Smaller dogs do not have the fast division of cells that big dogs have, which may increase the aging process.
Another theory has to do with concentrations of growth hormone. Studies suggest that small dogs have lower concentrations of the growth hormone in their blood than big dogs.
According to Kaeberlein, the lower the concentration of growth hormones in certain mammals has been shown to help reduce their risk of age-related diseases and thus help produce longer lives.
Kaeberlein and his colleagues are testing whether a drug called rapamycin can extend a dog’s life. When older mice were treated with this drug, their hearts became stronger and they lived up to 60% longer.
Kaeberlein and his team have been evaluating the drug in dogs, because they suffer from many of the same age-related diseases as people.
“We’re doing this in large dogs for the very reason that large dogs age faster than small dogs,” he said.
“We can actually assess whether something like rapamycin can improve heart function or improve cognitive function in a dog in a few years, whereas in a human that might take a decade.”
Project Funding
A grant from the National Institute on Aging is funding a project, called the Dog Aging Project, to explore the biological and environmental determinants of aging in dogs.
The project is based at the University of Washington and Texas A&M Veterinary Medicine & Biomedical Sciences in College Station. It’s a 10-year, $23 million project funded by the NIA, a part of the National Institutes of Health.
There are 30,000 dogs and their owners from across the United States participating in this aging study.
Scientists and research veterinarians from 20 research institutions and veterinary teaching hospitals are following the health and aging process of these dogs for 10 years or more to understand how genes, lifestyle and environment influence aging.
The study areas include:
- Genetics
- Microbiology
- Toxicology
- Canine cognition
- Age-related mobility
- Cardiology
- A clinical drug trial of rapamycin
“Aging is a complex phenomenon,” Kaeberlein said. “By combining insights from many areas of veterinary research, the Dog Aging Project aims to develop the field of veterinary geroscience and develop interventions that will help dogs live longer, healthier lives.”
Click here for more information on the Dog Aging Project.
To me, the older our dogs get the dearer to our hearts they become. Small or large our pals never live long enough.