As with any species, most disease processes are more common in older individuals. In cats, dental disease, hyperthyroidism, kidney disease, diabetes and some forms of cancer are among the more common.
Hyperthyroidism is caused by the over production of thyroid hormones due to, in most cases, a benign tumor on the thyroid. The hallmark hyperthyroid cat has increased activity, vocalization and appetite while exhibiting weight loss. They also tend to have increased thirst and urination. Treatments include radioactive Iodine, surgical removal (both curative) or daily medication for life.
In cats who do not brush their teeth daily (I dare say all cats!), normal oral bacteria produce an accumulation of plaque and tartar on the teeth. Left unchecked, dental disease can be very significant in the cat. Inflammation of the gums (gingivitis) and erosion of the teeth (feline oral resorptive lesions) are common findings in advanced dental disease. Many of these advanced cases require lengthy dental procedures and multiple extractions. Routine dental prophylaxis under general anesthesia can go a long way in preventing severe dental disease and help preserve your cats teeth well into old age.
Chronic Kidney Failure
Most cases of Chronic Renal Failure (CRF) in cats results from progressive and irreversible scarring of the kidneys (termed Nephrosclerosis). This progressive kidney dysfunction leads to diminished ability to remove waste from the blood and decreased ability to conserve the body’s water balance (leading to excess thirst and urination). The cause of nephrosclerosis is unknown. It is the number one disease of older cats and affects 1 in 5 cats over 15 years of age according to the Feline Advisory Board. There is no cure. Fortunately, most cats can be managed medically and live for years with CRF.
Diabetes & Obesity
Diabetes is common in obese older cats. The disease results in a decrease in insulin production by the pancreas and subsequent high blood sugar levels. If left untreated, diabetes can be a life threatening disease. The hallmark symptoms of sugar diabetes are excess thirst and urination and increased appetite. In almost every case of sugar diabetes, twice daily insulin injections are required to control the disease initially. The good news for cats is that with proper diet (a low carbohydrate canned food) many can ultimately be controlled with diet alone.