Why Do Small Dog Breeds Live Longer?

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In nature, the larger the animal, the longer their lifespan tends to be. Elephants live around 70 years, while mice only live for about a year. But in dogs, the opposite is true - the larger the dog, the shorter the lifespan tends to be. This is something that many scientists are investigating and no one really seems to have all the answers yet. A better question might be, why do bigger dogs die younger? It seems there could be a variety of factors, from more rapid ageing of large dogs’ chromosomes to breed-related issues such as heart disease and cancer significantly cutting lifespans of some large and giant dogs.

Why Do Small Dogs Live Longer?

One thing to keep in mind when talking about the average lifespans of small, medium, large and giant breed dogs is that these are average figures. This means that some dogs will live shorter than the average and other dogs will live longer. But if this is the case, why do small dogs live longer than large dogs?

It is believed that large dogs simply age more quickly than small dogs. It's not uncommon for some giant breeds to gain upward of 45 kilograms in a year, whereas some small breeds may only gain 5 kilograms. This rapid growth associated with some giant breeds appears to negatively affect their longevity. When looking at the average lifespans of dogs based on breed, there are often certain generalisations; however, even within the same size category, some dogs may live longer than others due to common health issues associated with a specific breed.

Cute Maltese sitting in a grass field

What Is the Average Lifespan of a Dog?

The average lifespan of a dog is dependent on whether they're a small, medium, large or giant dog breed — so the answer varies.

Small Breed Dogs

Smaller breeds, like the Chihuahua and Maltese, which are popular due to their portability, are considered on average to be less than 10 kilograms and have an average life expectancy of 10 to 15 years. However, the oldest known Chihuahua on record, named Megabyte, passed away at 20 years and 265 days old.

Medium and Large Dog Breeds

Medium dog breeds, like many of the spaniel breeds, are approximately 10-20 kilograms and large breeds, like the popular Labrador retriever and boxer, are usually considered on average to be greater than20 kilograms. The average lifespan for medium and large breeds is approximately 10-13 years.

Giant Dog Breeds

Giant dog breeds are usually considered to be greater than 40 kilograms. The average lifespan for a giant breed, such as the regal Great Dane, is unfortunately only 6-8 years, but some have lived to be 11-12 years old or older.

Further, mixed-breed dogs tend to live about 1.2 years longer on average than same-sized purebred dogs.

The current record for the longest-living dog based on Guinness World Records is held by a medium breed dog born in Australia in 1910, an Australian cattle dog named Bluey, who lived for 29 years and 5 months.

How Can Pet Parents Help Their Dogs Live Longer?

There are many things that pet parents can do to help their companion live a longer life, no matter what size or breed they have. The following can keep your pet happy and healthy:

  • Provide routine wellness veterinary care: This includes regular physical examinations, appropriate vaccinations and other preventative health care measures, including regular de-worming and flea/tick preventatives, routine dental cleanings and blood work monitoring, as directed by a veterinarian. This routine care can help any dog live a longer life.
  • Great Dane Dog Laying on bedSpay and neuter: Dogs can benefit from spaying or neutering in order to live longer. This reduces the risk of certain cancers - such as mammary, ovarian and testicular - or uterine infections (which can be life-threatening) and potential traumas/injuries. Speak to your vet about what age is best to neuter your size and sex of dog.
  • Maintain a healthy weight: Provide your pet with regular, daily exercise to keep them slim and stimulated too. Ask your vet about how much exercise is appropriate for your dog's size and age. The People’s Dispensary for Sick Animals (PDSA) warns that obesity can put dogs at risk of severe health issues and even reduce their lifespans. Maintaining an appropriate body weight places less stress on the joints and organ systems of the body.

Different breeds have certain health concerns that pet parents, along with their vet, should monitor. It's recommended that the pet parent learn about the characteristics and common health concerns of a particular breed or mixed-breed dog prior to adoption. This helps them to identify health concerns early on so that they can be addressed with the family's vet in a timely manner.

So, with routine vet care, exercise and lots of love, you can give your dog their best chance at living a longer, healthier life. And hopefully, with the continuing advances in veterinary care and nutrition, there will be a day in the future where we don't have to ask questions like "why do small dogs live longer than big dogs" anymore.

Contributor Bio

Jessica Seid

Jessica Seid

Jessica Seid is an emergency veterinarian practising in the New England area of the United States. She is a graduate of the North Carolina State College of Veterinary Medicine and has been in the field for more than a decade. When she's not helping patients, she enjoys spending time with her husband, daughter and dog.