My sweet Bella had her spay on Wed. My vet new about ACE and boxers and that it should not be used so I sighed relief. During her surgery her heart rate slowed and my vet said hers skipped a beat. Bella is fine and is recovering so well ( I don't know how we are going to do 7 days of no rough housing or burning). I can only imagine that if she was given ACE before her surgery things might have not turned out so well. So thank you for the invaluable information. I give high remarks to my vet too!!!