As your cat ages into his or her senior years it is ever more so important for you to attune to any behavioral changes in your cat as an indicator for any potential health problems. Due to their natural survival instincts cats are very good at keeping their vulnerabilities and health defects well disguised. Study your cat for any changes in activity or daily routine and consult your veterinarian. 

Many veterinarians agree that by the age of 12 years many cats experience the effects of old age. Although some cats may act older at 10 years while others enjoy a brisk pace at 15 years, the degenerative process begins anywhere between 10 to 12 years. 

There are six common diseases in senior cats, these are hyperthyroidism, chronic renal failure, hypertension, cancer, diabetes mellitus and inflammatory bowel disease(IBD). Cats may also suffer from liver disease, heart disease, neurological disease and lung disease

It is generally recommended that cats have regular exams up to two times annually if they are between  the ages of 7 to 11 years. If you'd like to start a preventative health program for your cat you can get a physical exam and the following diagnostic tests: CBC, blood chemistries, viral testing, urinalysis and blood pressure measurement.