710 DOSES AND THEIR ADMINISTRATION 



effects are desired, carefully regulated doses are given 

 every hour or oftener. Where continued effects are de- 

 sired, as in the case of tonics or alteratives, small doses 

 repeated three or four times daily are preferable to larger 

 doses given at longer intervals. Stimulants, which are evan- 

 escent in their effects such as alcohol, ether, and ammonia 

 are usually beneficially repeated every two or three hours, 

 or, in critical cases, oftener. The dose of a medicine, and 

 the desirability of its repetition, intermission, or suspension, 

 must frequently be determined by the manner in which the 

 patient is affected by the first dose or doses. 



The doses mentioned in this work under each drug, 

 unless otherwise stated, are those suitable for adult 

 animals of medium size. But, as already indicated, the 

 size, weight, and environment of the patient require con- 

 sideration in fixing the dose. In the lower animals, differ- 

 ences of sex do not materially affect dosage ; although, on 

 account of their larger size, extra doses are required for 

 stallions, bulls, and rams. Doses must be adapted to the 

 age of the patient. It is generally estimated that a one- 

 year-old colt requires one-third the quantity of any medicine 

 given to an adult horse ; a two-year-old, one half ; a three- 

 year-old, two-thirds. A somewhat similar ratio is applicable 

 to cattle. 



Medicinal agents are used to produce either local or general 

 actions, or a combination of both. 



LOCAL ACTIONS are produced by applying the agent to the 

 surface of the skin, to the mouth or throat, the eye, ear, or 

 nasal passages, and also by injection into the rectum, 

 bladder, vagina, uterus, udder, and substance of muscles. 

 Agents thus used, besides acting locally, may pass into the 

 general circulation, and produce general effects, or by 

 reflex action develop secondary or remote effects. 



GENERAL ACTIONS are usually produced by the introduc- 

 tion of the medicine into the circulation. Injection may be 

 made directly into the veins as in the treatment of collapse 

 and acute anaemia, and occasionally into the arteries, for 

 purposes of experiment. When transfusion is undertaken 

 the fluid should be watery, and of the same salt content as 

 blood serum ; for example, normal saline solution, a O9 per 



