Do small dogs really live longer than big ones?
We want our dogs to be with us for a long and happy life; that's all part of being a good owner. It makes sense, then, that animal lovers would have questions about their dog's life span, especially as it relates to their particular breed. There is a lot of misinformation out there, as well as some that could be confusing for owners.
Do small dogs live longer than large dogs?
Simply put, the answer is yes. It is widely known and accepted that small dogs live longer than large dogs. For example, a Great Dane is considered ”senior” at 7 years of age, while a Chihuahua is barely considered middle aged at the same age.
Why do large dogs have shorter life expectancies?
This is a fascinating question, especially if you have ever owned a small mammal such as a rat that only lives to about 2 years of age. You would think that a smaller size would lead to a longer life, but this just isn't true with small mammals. Take a look at elephants, for example; they can live as long as humans and they are huge!
Nature doesn't always follow specific rules. In April 2013, Dr. Cornelia Kraus from the University of Göttingen in Germany published some groundbreaking research on this subject to help determine the connection between size and life expectancy in dogs. Dr. Kraus analyzed data on the age of death in over 56,000 dogs from 74 different breeds. She found that small dogs do indeed live longer, and the researchers were actually able to quantify that number. Their findings indicated that for every 4.4 pounds (2 kg) of body weight, a dog's lifespan decreased by 1 month.
Dr. Kraus suggests that bigger breeds die more frequently from cancer than smaller dogs do. This may be due to the tendency of large breed dogs to grow faster, which may be associated with the abnormally fast cell growth seen with cancers and accelerate overall aging. Another risk factor may be that larger breed dogs could have more dangerous lifestyles than smaller breed dogs who are more “pampered”, thus increasing their risk factors.
Why do smaller dogs live longer?
The flip side of that question is that if big dogs live shorter lives, is there anything that makes small dogs more likely to live longer? Honestly, no one knows for sure. Here are some of the popular theories on the subject, though:
1. As mentioned above, it is believed that smaller dogs live longer because they grow more slowly than large breed dogs. Smaller dogs don't have the fast division of cells that big dogs have and can be associated with cancer and accelerate aging.
2. Another theory has to do with concentrations of growth hormone. Studies suggest that small dogs have lower concentrations of the growth hormone IGF-1, or insulin-like growth factor 1, in their blood than big dogs. Lower concentrations of IGF-1 shows reduced risk of age-related diseases and longer lifespans. In humans, high levels of IGF-1 have been associated with increased risk of death from heart disease and cancer.