Thiamine, otherwise known as Vitamin B1 is an interesting vitamin from the standpoint of horses. It is used in the horse world for two main reasons, which may appear at first glance to be contradictory: providing energy and calming.
During exercise, a compound called pyruvate is formed. Now, pyruvate can end up as lactic acid, which builds up in muscles and causes stiffness and muscle fatigue. Thiamine helps to stop pyruvate becoming lactic acid by converting it to Acetyl Co A. Studies by Topliff et al (1981) suggest that an exercising horse may need twice the thiamine that a non-working horse needs.
Another important function of thiamine is the transmission of impulses along nerves. So, a thiamine deficient horse will be irritable, nervous, jumpy, easily distracted and difficult to work with. Sometimes, supplementation with thiamine will help correct problems like these. Other times, it could be some other problem – genetic, training or other nutritional problems.
When there is not enough
Often the thiamine deficient horse is not an undernourished horse. On the contrary, thiamine deficiency often occurs in horses on high carbohydrate rations with rigid work loads.
Is it safe?
Thiamine is a water-soluble vitamin, and so supplementation up to 1000mg per day is very safe. Excess is simply eliminated by the kidneys.