B Vitamin Booster Syringe. MULTIPLEX is a B Vitamin booster syringe that can be given weekly to horses in training, to promote a good appetite or as a pre - competition booster. The B Vitamins play important roles in red blood cell physiology and in energy metabolism and are therefore key nutrients for exercising horses. Whether horses are capable of synthesising adequate quantities has been questioned. Increasing energy expenditure leads to an increase in the requirements of these essential B Vitamins. Horses can usually produce some B vitamins in their digestive systems, but changes in the environment, exercise, food or weather, or watery stools in the case of illness, can cause an imbalance. It is recommended that horses receive a regular and balanced supplement of B vitamins because it can be difficult to check for a vitamin B deficiency. The unique thing about B vitamins is that they are water soluble, so the body will eliminate an excess of B vitamins in the urine. It takes very