Photo courtesy of Dr. Sara Render Hopkins
Jada, a Labradoodle in Seattle, was fêted on her 15th birthday.
A plate of cookies and a silver tiara helped Jada the Labradoodle bring in her quinceañera, a celebration of Mexican origin held on a girl's 15th birthday. The tradition is meant to mark a child's coming of age, but in Jada's case, it signposted an achievement in longevity that many veterinarians suspect is becoming more common as the quality of pets' lives improves.
Among those practitioners is Dr. Sara Render Hopkins, a certified hospice and palliative care specialist in Seattle who counted Jada as a patient.
"I have been a veterinarian for 23 years, and I do think pets are living longer now compared to earlier in my career," Render Hopkins said. "For the last 10 or more years, my focus has been on end-of-life care, and even during this time, I think cats and dogs are living longer lives."
It's not uncommon, Render Hopkins said, for her clinic to see pets reach their late teens and early twenties.
Indeed, Jada's 15-year milestone, not unheard of for a Labradoodle, is no match for some other pets. Many are living much longer — more than twice as long in at least one case. Bobi, a purebred Rafeiro from Portugal, celebrated his 31st birthday in May, having been declared two months earlier as the world's oldest dog by the Guinness Book of Records.
Heartwarming tales of plucky old pooches aren't new, of course. Before Bobi, the record-holder for oldest dog was Bluey, an Australian cattle dog who died in 1939 at age 29 years and five months.
So are our favorite companion animals really living longer, on average, in the present day? Looking beyond mere anecdotal and circumstantial evidence and definitively answering that question is challenged by a host of factors. Most pets don't have birth certificates, and none have death certificates, making for limited data compared with the wealth of information available on human lifespans. And a pet's longevity can be influenced by complicating variables, such as breed and a relatively high frequency of euthanasia that's sometimes undertaken for reasons unrelated to health, such as economic hardship, pet aggression or human convenience.
Still, although the arena of pet life expectancy has been light on data, a recent batch of scientific research enables veterinarians to more accurately predict pets' lifespans and serves as a benchmark to determine whether lifespans are lengthening going forward.
By the numbers
Helping to establish a baseline, veterinarians at the United Kingdom's Royal Veterinary College and National Taiwan University recently compiled life expectancy tables for 18 dog breeds. The research, published last year in Nature, was based on data amassed through the RVC's VetCompass program, which collects clinical data from more than 1,800 participating veterinary practices in the U.K.
Dogs had an average life expectancy of 11.23 years, the study found, based on clinical records of 30,563 British dogs that died between January 1, 2016, and July 31, 2020. On the whole, female dogs, at 11.41 years, lived longer than males, at 11.07 years. Jack Russell terriers and French bulldogs had the longest and shortest life expectancies, at 12.72 years and 4.53 years, respectively.
In cats, separate research published this year that also is based on VetCompass data pegged the median life expectancy at 14.0 years, with Birman breeds living longest, at 16.1 years, and Bengals the shortest, at 7.3 years. Those results were based on a study sample of 4,009 cats with confirmed deaths randomly chosen from 118,016 felines attending 90 practices in central and southeast England.
The authors of both studies acknowledged limitations, including, for example, that the sole inclusion of veterinary practice-attending pets produced results that might be less representative of unowned animals or animals not attending veterinary clinics. Future studies might incorporate other sources of information, such as data from pet insurers, the researcher behind the dog life expectancy study said.
Still, they maintained their work provided a proof of concept that could support further research looking to assess changes in pets' life expectancy over time. Identifying research that already has attempted to measure such change is harder to come by and has tended to occur in the corporate realm.
One such study, published in February in Frontiers in Veterinary Medicine, pointed to a progressive increase in pet lifespan over a study period that started in 2013 and ended in 2019.
The study was conducted by Mars Inc., a conglomerate that owns more than 2,500 veterinary clinics worldwide and pet-food brands such as Royal Canin. The dataset included information on nearly 13.3 million dogs and nearly 2.4 million cats collected from more than 1,000 of Mars' Banfield Pet Hospital clinics in the United States.
The data on dogs confirmed that smaller breeds tend to live longer than larger ones. Between 2013 and 2019, the average lifespan of toy and small dogs increased by 5.62% and 5.0%, respectively, to 13.58 and 13.79 years. The lifespans of medium, large and giant-breed dogs increased by 4.51%, 4.27% and 6.59%, respectively, to 12.94, 11.70 and 9.70 years.
In cats, improvements in longevity were even more apparent. The lifespan of purebred cats increased by 9.31% over the study period to 11.85 years. The lifespan of mixed-breed cats increased by 13.69% to 11.69 years.
Apart from noting that the study omitted animals never presented to veterinary practices, the authors acknowledged there was a degree of uncertainty of pet age for dogs and cats acquired as rescued animals or adopted from animal shelters, among other limitations.
What do the numbers tell us?
Despite the inexact nature of the science, the Mars findings don't come as a big surprise to Jillian Edmonson, a registered veterinary technician and practice manager of a clinic in western Pennsylvania. Like Render Hopkins in Seattle, Edmonson believes pets are getting older because their owners are treating them more like family members. Their heightened status in the household has been accompanied by better access to an ever-improving quality of veterinary care and a healthier diet, she said.
"The [veterinary] industry has really advanced; it's human-grade medicine for pets. There are board-certified cardiologists and oncologists, for example," Edmonson said. "There are specialized diets for food allergies, treatments for common ailments like diabetes and kidney disease and more awareness overall of the importance of routine care. It may sound so obvious or trivial, but routine wellness checks really do increase the life expectancy of pets."
One element of Mars' research demonstrated a clear link between a dog's body condition score — a measure of body fat — and life expectancy: Obese dogs in the study died younger, by 1½ years on average, than dogs with a median body weight.
Nestlé, one of Mars' biggest competitors in the pet-food realm, has examined the effect of caloric restriction on longevity in dogs. Its Purina pet food division looked at the feeding habits of 48 Labrador retrievers over 14 years. That research, published in 2002, found that 24 dogs fed 25% less food than matched littermates lived, on average, 15% longer — 13.0 years compared with 11.2 years in the controls.
In Hungary, a study conducted by researchers at Eötvös Loránd University and published in 2018 examined many factors that may impact dog life expectancy, ranging from trauma history to food choice to the amount of time spent playing. The data came from responses to an emailed survey of Hungarian pet owners, who provided information on 1,207 individual dogs. Of note, dogs that were overweight or had a previous traumatic life experience had shorter lives. High-quality food and regular veterinary care were predictive of longer lifespans.
In short, Render Hopkins observes, scientific research supports what veterinarians have been telling clients all along: "High-quality food, keeping your pet at a healthy weight, and plenty of exercise are factors that can increase life expectancy. Socialization and training are also important — many pets are euthanized for behavioral reasons."
Dr. Monica Tarantino, founder of the Senior and Geriatric Dog Veterinary Society, has spent much of her career working to improve the lifespan — and quality — of canine lives. She points to another factor in longevity: spaying and castration. "When done at the appropriate times, it helps reduce the risk of certain types of cancer and disease such as mammary cancer, pyometra and testicular cancer," Tarantino said. Neutering also reduces the propensity for risky behaviors such as roaming, she added, pointing out that intact male dogs are more likely to get hit by a car than neutered male dogs due to a tendency to roam in search of females.
Beyond that, Tarantino points to research indicating that pets that receive rabies vaccines have reduced mortality rates from all causes of death. The researchers weren't sure why but postulated that the vaccine might confer protection to infections beyond rabies.
"And certainly, if owners are able to pursue more targeted care with specialists when the need or recommendation comes up, this will also have a great impact on a pet's life," Tarantino said. "Lifestyle choices for our pets, such as keeping them indoors or fenced — for dogs — reduce their likelihood of getting hit by a car, being exposed to infectious agents in the environment, extreme weather changes and even predation."
Where might it end?
If dogs and cats really are living longer, what are the limits? Nobody is quite sure why certain types of animals have longer or shorter lifespans etched into their DNA. It was long assumed that a higher metabolic rate — the amount of energy needed to keep a body functioning — is associated with faster aging and a shorter lifespan, such as is seen in dogs and cats. But that theory is confounded by the fact that some other animals with high metabolic rates, such as parrots, can live for many decades.
Evolutionary pressures also are theorized as swing factors: Animals that are more vulnerable to predation are more apt to grow and reproduce quickly in order to protect themselves. Consequently, the theory goes, larger animals typically live longer because they are harder to prey upon and don't have to rush. That idea is turned on its head, though, when it comes to dogs, which tend to live longer the smaller they are. Scientists at the University of Adelaide in Australia think they know why. In research published in May in The American Naturist, they postulate that selective breeding for size has made large breeds more susceptible to cancer.
Photo courtesy of Dr. Sara Render Hopkins
Roy, a schnauzer-poodle mix belonging to Dr. Sara Render Hopkins, a palliative care and hospice veterinarian in Seattle, is 17½ years old.
With those kinds of nuances in mind, sophisticated efforts to extend dogs' lives are underway. At the Dog Aging Project, a study based at Texas A&M University and the University of Washington, researchers are zeroing in on how genes, lifestyle and environmental factors affect aging in dogs. Their ongoing work provides insights they hope will advance the cutting edge of veterinary care and perhaps help extend dogs' lives.
For instance, they currently are recruiting dogs for research involving the drug rapamycin, which affects the immune system and metabolism. In one previous study, rapamycin was found to increase the lifespan of mice — slowing cognitive decline, as well as reducing the occurrence of tumors, cardiovascular disease and immune-system dysfunction.
Elsewhere, the biotech company Rejuvenate Bio claims to have extended the lifespan of mice using gene therapy and is working on developing similar therapies for pet dogs, with the ultimate aim of extending the lives of humans. (The research on mice was published as a preprint in January. It hasn't been peer reviewed).
A good life is more than a long life
Tarantino stresses that keeping dogs and cats alive as long as possible isn't necessarily a good thing. Veterinarians and pet owners, she said, should aim to ensure quality of life, too.
Focusing on "healthspan," or the amount of time an individual is free of significant disease, is a key consideration for Tarantino as she helps clients navigate their emotions when making decisions about geriatric pets.
Such decisions can be hard, as Render Hopkins knows all too well. By the time of this story's publication, she had euthanized Jada. The Labradoodle was put to rest in her backyard, surrounded by loved ones.
Render Hopkins' own dog, Roy, a schnauzer/poodle mix, is 17½ years old. The veterinarian knows she eventually may have to decide whether keeping Roy alive is the most humane option.
"As an end-of-life-care veterinarian who has helped thousands of families say goodbye to their pets, I have seen many situations where people may have kept trying to prolong quantity of life over quality," she said. "Those years should not happen at all costs, and I think that is something that people can lose sight of."
Ross Kelly contributed to this report.