Cause
Genetic differences in cats are partially responsible for the individual differences in spraying behavior among cats. Facilitated by the male hormone testosterone, urine marking occurs primarily as a response to stimuli from other cats because the presence of urine odor may initiate and perpetuate spraying within the household. Thus, cats that live in multiple cat households are much more likely to spray than cats that live in single cat homes; the incidence of spraying in single cat households is 25 percent, while in households or facilities containing 10 or more cats, the incidence is measured at 100 percent. Once spraying develops within the home, there is often a learned association between spraying and specific sites, which then become established "marking-posts."