Generally speaking, large mammals like elephants and rhinos, live longer than small mammals, like mice and guinea pigs. However, when speaking about dogs, this is not true. It is well-established that smaller dogs live longer than large dogs. For many years, this peculiar phenomenon has baffled scientists. The relationship between body mass and life expectancy is quite complex and not fully understood. Nevertheless, recent studies suggest that a dog’s life expectancy is reduced by 1 month for every 2 kilograms of body mass. The reason why is not known but there are several evidence-based and objective options:
- Larger dogs tend to succumb to age-related illnesses sooner than smaller dogs
- Due to their accelerated growth, larger dogs are at higher risk of abnormal cell growth and consequently cancerous changes.
Great Danes grow quickly in size but do not reach maturity until 2 years old. Their average lifespan is 6-8 years. On the flip side, Yorkshire Terriers reach maturity when less than 12 months old and have a particularly long lifespan that often exceeds 15 years. Therefore, both the lifespan and the ageing rate depend on the breed.
A 4-year old Miniature Schnauzer is younger than a 4-year-old Neapolitan Mastiff. However, since smaller breeds mature more quickly, it is only logical to assume that a 1-year-old Chihuahua is more mature than a 1-year-old Great Dane.