Large Breed Longevity. The average lifespan of all dogs -- both small and large -- is 12.8 years, reports pets.ca, a Canadian pet information provider. Some larger dogs tend not to live that long, and data varies considerably by breed.
Aching Legs. Aching Legs and Feet. Injury is the most common cause of leg pain (aching legs). However, even a simple back pain can cause your legs to ache depending on the degree of pain. Usually, elders and diabetics and people with poor circulation are the ones who experience leg pain especially at night.
The tired, aching or heavy legs phenomenon is common that we all experience from time to time, particularly at the end of the day and in the summertime. In particularly, it is normal to have those legs feel like tree trunks after a rigorous exercise or a day at an amusement park. It is simply due to fatigue.