I have had an almost similar situation.  You may want to read my thread.  
  http://www.yorkietalk.com/forums/yor...i-give-up.html 
The only Acana food that I found with a lesser protein content is not available in the U.S. - the Lamb and Apple.  The 3 availabe in the U.S. all had high levels of protein.  Excellent food though - and my dogs did love it - but unfortunately did not agree with their system.  Both Orijen and Acana are great foods - but did not agree with my little guy. 
Good luck to you.