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.
There are many medical conditions that can cause leg pain. 1  Fibromyalgia sufferers frequently experience restless leg syndrome and painful lower leg cramps.  Leg pain can also be associated with autoimmune disorders such as multiple sclerosis and rheumatoid arthritis. Thyroid disease can also cause pain in the legs.