130 INORGANIC AGENTS 



contractions of the heart stronger and slower. The salt stimulates direct- 

 ly the heart muscle. Lethal doses are followed by slower and slower 

 ventricular contractions^ succeeded by peristalsis of the cardiac muscle^ 

 and, finally, by stoppage of the heart in systole. 



Barium chloride also directly excites the muscular walls of the capil- 

 laries, and thus contracts the pulmonary, cerebral, and coronary arteries 

 which lack constrictor fibres. 



Muscles. — Barium chloride stimulates muscular contraction when it 

 is applied locally. It stimulates contraction of the uterus, bladder and 

 other organs. Toxic doses, given intravenously, cause convulsions owing 

 to stimulation of the spinal cord and medulla. Thus there is initial 

 stimulation of the medullary vagus, vaso-motor and respiratory centres, 

 with rapid respiration. This is succeeded by paralysis of the central 

 nervous system. 



Summary. — Circulatory stimulant, and purgative in large medicinal 

 doses. 



Uses. — Many practitioners are afraid to use barium chloride, but 

 repeated use of the drug has convinced Muir that it is safe when given 

 in the dose of 1 gram or 15 grains, intravenously, or 4 to 8 grams (1 to 

 2 drams) by the mouth in solution for the horse.* Barium chloride is of 

 value in colic and obstinate constipation of horses. It may for the time 

 cause some increase of pain but not nearly as much as follows the use of 

 eserine or arecoline, and it quickly passes off when the bowels are moved. 

 Great care should be exercised to avoid introduction of the barium solu- 

 tion into the connective tissue while injecting it into the vein. The 

 needle of the hypodermic syringe should be introduced into the jugular 

 about midway of the neck, and after some drops of blood have exuded 

 from the vein, the syringe is attached and slowly emptied, when the 

 plunger is withdrawn until some blood enters the syringe. Then the 

 needle may be removed with safety. It is rarely necessary to repeat the 

 dose of barium chloride, and small doses of extract of cannabis may be 

 • given to lessen colic while barium is acting, when it is given by the 

 mouth. 



Extensive experiments of Muirf with barium chloride lead him to 

 conclude that the salt may be administered intravenously in the amount 

 of 1.0 to 2.0 Gm. (15 to 30 gr.) in 1 to 2 drams of sterile water; that " 

 2 Gm. is a safe dose by the intra jugular method for a horse of ordinary 

 weight and fair condition ; that the drug acts promptly when given in this 

 way, catharsis being produced within one to nine minutes, and that even 

 volvulus may be relieved; that there are no unpleasant symptoms follow- 

 ing the smaller dose (1 Gm.), and that even after the 2 Gm. dose there 

 are only slight signs of pain and sweating; that while the passages from 

 the bowels are few in number the total amount of feces is large; finally, 

 that the drug has the advantage of being cheap. 



*Lockhart reports two deaths in horses from 2% and 3 drams of barium 

 chloride by the mouth and he warns that the efficient cathartic dose approaches 

 the lethal limit with this drug. (Amer. Vet. Review, Apr., 1914..) 



fJour of Comp. Med. and Vet. Archives, Jan. and Feb., 1899. 



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