Properties.—A colorless, transparent, monoclinic prism, flaky, lustrous leaflets or a white crystalline powder; permanent in air, containing no water of crystallization; odorless; of a saline, slightly bitter taste, and producing on the tongue a tingling sensation followed by numbness of several minutes’ duration. Soluble in 0.4 part of water, 2.6 parts of alcohol and in 18.5 parts of chloroform at 25° C. (77° F.); soluble in benzine, petroleum benzine and ether. It leaves no residue on incineration. Its aqueous solution is neutral to litmus paper.
Dose.—Horses and cattle, 5 to 20 gr.; sheep and pigs, 1 to 3 gr.; dogs, 1⁄8 to 1 gr. Not much used internally.
Action.—Cocaine in small doses is a cerebral, cardiac, respiratory and nervous stimulant and dieuretic; overdoses cause delirium with cardiac and respiratory failure. Cocaine is a powerful local anaesthetic; used for all animals in 4 to 10 per cent solution, usually a 4 to 6 per cent solution is strong enough for ordinary operations. Inject under the skin, into the muscular tissue or over nerve trunks for minor operations. Applied to such structures as the eye, penis, tongue and other delicate mucous surfaces as the uterus, vagina, rectum, etc. It causes profound but temporary anaesthesia over a small area; it causes rapid and extreme dilation of the pupil.
Cocaine is injected for minor operations to prevent pain, such as neurectomy, removing tumors, operations on the eyes, tongue, fistulae, firing, etc. For dogs it should be used with great caution, a two per cent solution usually being enough and as little as possible being used.
For the horse, as a rule, not more than two drachms of a five per cent solution should be injected subcutaneously, lest restlessness, excitement, etc., ensue, which though not necessarily dangerous, may interfere with the operation.
In using cocaine as a diagnostic agent for lameness, the fact must not be lost sight of that it is a cerebral stimulant and that if a large quantity is injected it may cause such a degree of excitement as to make the patient forget his lameness, thus leading the operator to believe that the improvement is due to anaesthesia below the point of injection, when the apparent remission from the lameness is of physical origin. Cocaine is advantageously used in painful eye affections. Its effects may be prolonged and the danger of its use lessened by dissolving the cocaine in a 1 to 1000 adrenalin chloride solution.
CRETA PRAEPARATA—PREPARED CHALK
Derivation.—Native calcium carbonate, freed from most of its impurities by elutriation.
Properties.—A white, amorphous powder, often molded into conical drops; odorless and tasteless; permanent in the air. Almost insoluble in water; insoluble in alcohol.
Dose.—Horses, 1 to 2 oz.; cattle, 2 to 4 oz.; sheep and pigs, 2 to 4 dr.; dogs, 10 gr. to 1 dr.