The unfotunate condition of being a meat head!

Daisy is a meat head!  A big one!!  For days, we've been trying to introduce Matt the Cat to Daisy the dumb saint bernard and it hasn't gone well.  Why?  cuz Daisy is a meat head!  Matt the cat is completely willing to have Daisy in his space.  He sits politely and they touch noses and sniff and Matt the Cat doesnt' bat an eye!  The problem happens when the Meat Head gets so excited that she wants to climb on top of Matt the Cat and sniff him all over and squeel and play and whatever the hell else she thinks she can do with a teeny tiny Matt the cat - Matt the cat will hiss - Daisy doesn't get it - Matt the cat will hiss a 2nd time - Daisy doesn't get it...Matt the cat will swat (without making contact) and Daisy STILL doesn't get it!  And whe Matt the cat tries to sneak away...the moron Meat head follows!!!  AUGH!  I even took her to the dog park last night to run off some crazy - hoping it would settle her down but it has been a full week and she's still laser focussed on the freakin cat!!  AUGH!  I'm about ready to lose my mind!  Maybe i could slip Daisy an ativan...??  spose that'd be bad??