What is the additives with milkshake for racing horses?

Milkshaking is the term used when a solution of bicarbonate, water and vitamins are given to a horse prior to a race. The theory is that the bicarbonate will neutralize the lactic acid produced during the race, and result in the horse getting less tired, especially towards the end of the race. A stomach tube is place into the horse's nose (not mouth), down the esophagus and into the stomach. Tests have not shown any conclusive advantage doing this procedure, but it is still illegal. A milkshake will rarely kill a horse unless something inappropriate is added to the mixture, or the tube is accidentally placed into the lungs instead of the stomach.