3 words, your comments are right on.

If the USA (rcalf) believe that  Canadian beef is so dangerous, then why haven't they rounded up all the Canadian cattle in the USA and had them destroyed and tested for BSE?

The fact that we might actually find an American born animal with BSE looms LARGE over their futures.  In fact, if we continue to be treated in this unfair manner; Canada should round up all the American born cattle in Canada and test them.