Abnormal or unpleasant odors may be caused by diseased or necrotic tissue in the respiratory or upper gastrointestinal tracts, including mouth and nasal cavity. Diseased teeth are a common cause in dogs and cats. In addition, certain metabolic diseases may produce distinctive breath odor, e.g. ketoacidosis, uremia.
Practically elderly is a person who needs special consideration due to advanced age. Which can happen in late 50s or in late 80s. If he or she can punch your lights out for calling them elderly, and you cannot run from them either, they possibly aren't.
However, there are at least two reasons for considering anemia in the elderly as a sign of disease. First, most older people maintain a normal red cell count, hemoglobin and hematocrit. Second, in most elderly patients an underlying cause of anemia is found for hemoglobin levels of less than 12 g per dL.5.