This paper describes the relationship between externalities and environmental regulation in the USA hog sector to verify the possibility to increase the stringency of regulation concerning externalities caused by hog manure in Brazil. The analysis shows that if the regulation reform in Brazil is going to follow the one in the USA it should be a government iniciative through the definition of national polluting standards based on hog manure rules already in place by the Brazilian states. Public funds would be required to enforce and punish polluters, and also to support farmers to acquire environmental inputs. On the other side, social pressure would be confined from the action of isolated groups related to environment, agriculture and farmer's work extension. The main conclusion is that there are no economic, social and institutional factors indicating the feasibility of such reform in the short run.