These terms are applied to drugs whose action improves the nutrition of nerve-substance, and thus strengthen and brace up the nervous system generally.

In our patient, the horse, we have not those hysterical conditions and obscure nervous diseases to deal with that have called into existence a number of specialists among human practitioners, yet it may be said that of all domestic animals the horse is the most "nervous" or excitable. From a variety of causes he is liable to become "run down", and a nerve tonic or stimulant is often the remedy most calculated to pull him up again.

It has been observed during recent years that the symptoms of nervous collapse have been very marked in most of the attacks of so-called influenza. The close observer, brought up among horses and familiar with their habits and expressions, can hardly doubt that they suffer from nervous headache and depression of spirits at times, giving rise to sleeplessness, timidity, and other indications of cerebral disturbance, and there can be little doubt that many of those sudden periodical changes of temperament and habit frequently observed in horses, and attributed to vice, have their origin in disorders of the nervous system.