Just like humans, there are many factors that influence a horses emotional stability. However, because they are prey animals, their ability to sense change  is much more refined and will often trigger their natural fight or flight instinct.  
Some of the environmental factors that increase stress levels include: travel, changes in routine, fear, pain and over or under exercise.  
Of course stress and anxiety may reduce a horses ability to concentrate and perform at their best, so anything we can do to make sure they get enough exercise, remain pain free and comfortable in their surroundings will go a long way in management of the nervous, hyper horse.  
But what other factors influence the horses ability to deal with stress?    
I'm glad you asked, because there are some nutritional factors may provide insight into successful management and may allow you to work through training and trust issues more effectively.   
The B vitamin Thiamin (Vitamin B1) plays a vital role in nerve function and horses with deficiencies may show trouble maintaining proper focus.  Magnesium is responsible for normal muscle relaxation, contraction & nerve impulses. Deficient horses may show a tendency to become nervous, excitable and may even experience muscle tremors.  And if a horse is deficient in Iodine, the thyroid gland will secrete too little of the metabolism regulating hormone, thyroxine, which can make horses nervous, hyper and/or irritable.
Calm-The-Storm combines the support of Iodine, Thiamin and Magnesium all in one supplement offers a comprehensive approach to successfully managing the nervous, hyper or irritable horse.   
Calm-The-Storm will not dull performance and 
many horses show an improvement in their ability to focus rather quickly.  Try it for 30 days, if you are not completely satisfied, we'll give you your money back!  
Nutritional Support for:
       •   Nervous horses
       •   Hyper horses
       •   Stall walkers

Calm-The-Storm to balance the system and Performance Plus or Performance Horse MAX for optimum nutrient balance moving forward!   

For a list of available products, see TLC Animal Nutrition, Inc