A mad cow disease (Bovine Spongiform Encephalophy) is a chronic, degenerative disorder affecting the central nervous system of cattle.  Bovine Spongiform Encephalophy is stood for by BSE.  Since May 2003 an Alberta cow was diagnosed having a mad cow disease, there have been two others that were found with the disease.  The affair has been affecting the relationship between U.S. and Canada since then.  It was supposed that the border between U.S. and Canada could be reopened on March 7^th, 200X but it was not.  Some body said that the politics had more effects than science did because Canada refused to sign on to a North American missile defence program.  They said that cow younger than 30 months is often described to be at very low risk for BSE.  I do not totally agree that politics completely substitute science in this case.