@katbriar , whatever you decide to get, ignore the dosing directions on the bottle or tube (horses), they're for goats, cattle, sheep, etc, not for chickens. Don't ask me why, but chickens, gamebirds and waterfowl get more per pound than the grass eaters.
The most effective Valbazen dose is 0.08ml per pound (20mg/kg). An average sized Rhode Island Red hen would get about 0.5ml (1/2 cc).
-Kathy
I actually got Tylan for pigeons and the dose was unreal. 1 tsp per liter! But different animal actually.