142 DEPRESSANTS TO CENTRAL NERVOUS SYSTEM 



Metabolism, The excretion of carbonic acid is diminished 

 during the depressant stage but in animals in which excitement is 

 produced, it may be increased due to increased muscular move- 

 ment. There may be an increase of lactic acid in the blood and 

 urine and a disappearance of glycogen from the liver on account 

 of the poor respiration. 



Treatment of Poisoning. Evacuate the stomach vs^ith the 

 stomach tube or stimulating emetics such as sulphate of zinc or 

 copper, or mustard, but on account of the depressant action of the 

 nervous system, emetics are uncertain and the stomach tube is to 

 be preferred. The stomach should be evacuated at frequent inter- 

 vals to remove the drug as it is excreted into this organ. Potassium 

 permanganate should be administered at intervals to oxidize the 

 drug for the same reason. The above measures hold good no mat- 

 ter hov? the morphine may have been administered, as it is elimi- 

 nated by the stomach in large amounts. Maintain the respiratory 

 and circulatory systems with stimulants, of which caffeine appears 

 to be one of the best. Atropine was considered at one time to be 

 antidotal, but must be used in very small doses for this action 

 because large doses are in themselves depressant to the respiratory 

 center. They may, furthermore, cause serious constipation as men- 

 tioned under discussion of the action upon the digestive tract. The 

 animal should be kept awake by exercise, dashing of cold water upon 

 it, etc. Artificial respiration should be used if the respirations cease 

 before the heart stops beating. 



Contraindications. Young animals are quite susceptible to 

 morphine and opium so that considerable care should be used in 

 prescribing for them. Morphine is not indicated in respiratory 

 diseases associated with excessive exudation, in cerebritis, high fever, 

 or constipation. 



Therapeutics. Morphine and opium are used to relieve pain, 

 overcome nervousness and excitability, lessen reflex excitability, 

 diminish secretions, support the system and as diaphoretics. 



Pain. Opium is not of so much service to relieve pain and 

 spasm in veterinary medicine as in human therapeutics because it 

 cannot be relied upon in any animal except the dog. Small doses, 

 however, are usually sedative to the horse so that the drug is 

 especially indicated in strong persistent pain such as in enteritis. 

 It may often be extremely useful in spasmodic colic and prodxices 

 its action here by arresting the irregular and violent peristalsis 

 which is the cause of the pain. It may be combined with small 

 doses of atropine or belladonna for this purpose. 



To Chech Peristalsis. Opium is very serviceable for this pur- 

 pose in various intestinal troubles, especially acute intestinal 

 catarrh and diarrhea. By checking both peristalsis and secretions, 

 an opportunity is given for a chance of repair, and permanent cure. 



