ACTION AND USES OF MEDICINES. 153 



These beneficial effects, however, are only produced when the system 

 has need of such artificial stimulus. When given to healthy animals 

 tonics are likely to do more harm than good. 



They differ from diffusible and other stimulants in that their action is 

 but slowly established, whilst their effects are tolerably permanent, and 

 their administration is not succeeded by subsequent depression. 



Tonics, especially mineral tonics, should not be given to horses except 

 under the advice of a well qualified Veterinary surgeon. Even in the 

 human subject great care is required in their administration; but they 

 may be more safely given, because the effect which they are producing 

 can be ascertained daily by inquiry from the patient. In the horse, how- 

 ever, we have not this advantage. We may watch for, but we cannot 

 positively ascertain their effect, until perhaps they have produced a 

 marked result, either for good or for evil. 



The medical tonics in ordinary use are divided into the two heads of 

 mineral and vegetable. The first named comprise salts of iron and 

 copper and arsenic. They are generally given with the food. The vege- 

 table tonics in common use are infusions of gentian, quassia, and cinchona 

 (which contains the alkaloid known as quinine). Ginger, aniseed, and 

 other aromatics have also a slight tonic effect. Mineral are far more 

 powerful than vegetable tonics. 



The cordial balls so much patronized by grooms generally contain as 

 their principal ingredient some mild tonic, such as gentian, cardamom 

 seeds, &c. 



The really best tonics for the horse, except after seriously debilitating 

 illness, are good fresh cool air, well regulated exercise, good feeding, and 

 good grooming. 



Of mineral tonics the ordinary dose may consist of 

 Sulphate of Iron 1 to 2 drachms, with 2 to 4 drachms of Ginger, 



or 

 Sulphate of Copper J to 1 drachm, with powdered Gentian 2 to 4 drachms, 



or 

 Arsenious acid ... . . . 5 grains. 



Though the above are the ordinary doses, yet it must be remembered 

 that Mineral tonics are very powerful, and even dangerous medicines, 

 unless their effects are closely watched. Hence the amount and fre- 

 quency of the repetition of the dose may often require to be varied under 

 the ever changing circumstances of the patient. 



Of Vegetable tonics the ordinary doses are 



Quinine J to 1 drachm, dissolved in a few drops of sulphuric acid and 

 a pint of water, 



or 



Oak bark 2 to 3 drachms made into a ball with treacle and bran, 



or 

 Powdered Gentian root 1 to 2 drachms, 



or 

 Tincture of Gentian 1 to 2 ounces in a pint of water. 



In some cases the above quantities may be doubled, 



