Found at vintagetribune on Instagram:
Original caption alert: Soon the only “snorting steeds” that will rush forth from Chicago fire houses at the sound of the gong will be the kind that feed on gasoline. Engine company No. 11 is the last station to be motorized. Dobbin, the horse at left, and his mate, Tip Top, have been ordered sold, circa 1923. It will be hard parting, for the horses are more than mere working companions. Left to right are Fireman James F. Kelly, Lieut. William Both, and Fireman Frank O Leary. #vintagechicago
thanks Austin