--In the Function window (right)
function bu(u, b)
	local i = 1
	while (UnitBuff(u, i)) do
		if (string.find(UnitBuff(u, i), b)) then
			return true
		end
	i = i + 1
	end
	return false
end

--In the Macro window (left)
/script if bu("Pet","Prowl") then UseContainerItem(0, 1) else TogglePetAutocast(7) CastPetAction(7) UseContainerItem(0, 1) end