Got it:
Set PetFacing = angle(0,0,cos(angle(Player.X,Player.Y,Pets.X,Pets.Y)-Player.Angle+90),sin(angle(Player.X,Player.Y,Pets.X,Pets.Y)-Player.Angle+90))
If PetFacing >= 0
Else
Thanks dude - we were on the right track but you got me thinking about it more. NeoGAF helped push me over the edge.