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.
It's important to know what the causes are and how to best handle seniors who are experiencing them. Hallucinations in elderly are abnormal sensory reception-usually auditory or visual-that the senior experiences while they are awake. The senior is seeing or hearing things that are not really there.