Epidemiology is the study of disease patterns. How common diseases are? What age ranges are they likely to affect? Are particular breeds predisposed to particular diseases? For example, did you know that the approximate incidence of diabetes is 1 out of every 200 cats; the incidence of diabetes is 1 in 50 for Burmese cats and 1 in 10 for Burmese over 8-years-of-age (which also means that 90% of senior Burmese are NOT diabetic!).