DRUGS WHICH ACT UPON THE NERVOUS SYSTEM 481 



with 01' used in conjunction with it. Besides allaying pain and spasm 

 when externally applied or internally administered, it would seem to be 

 specially beneficial in its action upon the organs of vision and upon the 

 urinary and generative apparatus. The puj^il of the eye is dilated, either 

 by internal doses or the more convenient method of dropping a solution 

 of atropia on the surface of that organ. In some diseases in which the 

 iris is liable to become fixed to adjacent parts under conditions of infiam- 

 mation, this is prevented by causing the pupil to be dilated and removing 

 the iris from contact with the structures referred to. 



Opium has the contrary effect, and causes the pupil to contract. 



In irritability of the bladder and kidneys belladonna is found to be a 

 valuable drug, controlling jjain and inducing normal secretion, while its 

 properties render it of great value when injected into the uterus of 

 mares after painful labour or inffammatory action from e version or other 

 accident. 



The preparations of belladonna used in equine practice are the extract, 

 tincture, liniment, and plaster. 



Atropia, its active principle, is invariably employed in solution, either 

 as drops for the eyes or for subcutaneous injection. 



Hyoscyamus or Henbane is a drug of like therapeutic eflect to 

 belladonna, but not in general repute among veterinarians. It may, 

 however, be employed with ad^•antage in the few cases where some idio- 

 syncrasy brings disappointment to the prescriber who has given bella- 

 donna. Its action is invariably milder and the results apparently better 

 when given in combination with some other sedative. 



Tobacco. — This powerful narcotic is more in favour with amateur 

 horse doctors than with veterinary surgeons. The manufactured tobaccos 

 are very variable in medicinal power, and when required as a drug 

 Virginian shag is usually selected, as containing more resinous and albu- 

 minous matters, which in other kinds are more or less removed by 

 partial fermentation. 



Action and Uses. — Externally a^^plied it is more or less irritant. 

 Internally it causes muscular relaxation, and in this way acts as an 

 antispasmodic in bowel and other aff'ections. 



An infusion of it is employed for the destruction of external parasites, 

 and is often apjilied in conjunction with sulphur in cases of mange. 



It is sometimes given to destroy worms in the intestines, and a small 

 plug of it introduced into the rectum with the view of getting rid of 

 ■■fundament" bots and other parasites which infest the terminal portion 

 of the bowel. Tobacco smoke injected into the rectum by means of 

 suitable apparatus appears to give relief in some cases of colic. 



ViiL. II 65 



