Interaction effects of epidemiologic factors in the feline urological syndrome.

Disease-associated factors are most often evaluated individually, while as disease determinants they act in mutual combinations. Applying simple epidemiologic methods, the present study evaluates the effect on occurrence of the Feline Urological Syndrome (FUS) of combining categories within sex, diet and activity. Some factor interactions could be described as additive, while certain combinations acted in a synergistic fashion. The apparent overall effect which might be explained by the excess-risk categories within these three factors was found to account for approximately 90% of the total occurrence of FUS in the population at risk. As a further result of the epidemiologic methods applied, a possible pathogenesis is outlined. It involves relative impairment of kidney function affected through two pathways: increased kidney working load and decreased kidney capability, both associated in various ways with castration, high levels of dry cat foods, and indoor confinement.