When your beloved pet is in his or her golden years, it becomes more important than ever to perform semi-annual comprehensive physical exams as well as diagnostic testing.  You've heard the adage that dogs and cats tend to age seven years for every one human year, so an exam every six months would be comparable to an elderly person visiting a doctor approximately every three years.  The likelihood of acquiring several diseases increases with age.  A semi-annual exam will aid in early detection of various diseases, and this may prolong the quality of your pet's life.  Senior pets can suffer from a variety of diseases, including, but not limited to, cancer, arthritis, heart disease, liver disease, kidney disease, diabetes mellitus, and endocrine disorders.