How long do dogs live is a common question. The answer requires you to consider many factors, which include breed mix and size, and environmental influences. In general, smaller dogs live longer, from 14-22 years, with medium sized dogs living 11-14 years and large dogs living 8-12 years. Mixed breed dogs tend to live longer as many purebreds suffer from breed specific genetic problems that may shorten lifespan.
Diseases of the neurological system can also cause lethargy, and examples of these include fibromyalgia and Parkinson's disease. Diseases such as these have joint discomfort or stiffness, which may cause those affected to move less. Since they cannot move well without pain, this may increase their lethargy.
Two common reasons for tiredness or lethargy are having too high or too low blood sugar levels. In both cases, the tiredness is the result of having an imbalance between oneâs level of blood glucose and the amount or effectiveness of circulating insulin. If you feel tired during the day, despite having slept well, it could be a result of either high or low sugar levels. It is best to test your blood glucose levels to see whether the tiredness is indeed a result of having high or low sugar levels. This is particularly important for people on insulin. 1  Read about the recommended blood glucose levels ranges.