Feeding to the nervous  system. Here is a combination of herbs which have  been used for years with success for the relieving of nervous tension.  They are classed as nervines and have a relaxing effect without causing drowsiness and will not affect performance in a detrimental way. They contain no prohibited substances. This is the ultimate calmer as it can be used long term and has been successful in helping many headshakers. Also for damage to nerves through trauma or injury.
 'Settle' - a different combination of herbs, a liquid calmer for quicker absorption can be given at the same time as a horse being on Relaxer on an occasion when extra quietness is needed, e.g clipping, travelling, times of particular anxiety or feral horses. 
Relaxer - nerve aid is a powder added to feed or mixed with water and syringed orally.