Effect of aging on body systems of the dog.

A common property of all aging systems is that of progressive and irreversible change, which may be hastened by the effects of disease, stress, nutrition, exercise, genetics, and environment. Current knowledge and technology provide increasing opportunity to effect change and improvement in the pursuit of health, longevity, and enhanced quality of animal life. Older animals seldom have a single disease, but rather each one represents a unique combination of varying levels of loss of function at both the cellular and systems level. Veterinarians should not accept that poor health and old age are inevitable companions. Knowledge of the common pathologic changes associated with age and their effect on function allows the clinician to plan more effectively and manage health care programs.