Opium and its alkaloid, morphia, are so commonly used in the practice of medicine that the poisonous result of an overdose is not uncommon. The common preparations are gum opium, the inspissated juice of the poppy; powdered opium, made from the gum; tincture of opium, commonly called laudanum; and the alkaloid or active principle, morphia. Laudanum has about one-eighth the strength of the gum or powder. Morphia is present in good opium to the extent of about 10 per cent. In medicine it is a most useful agent in allaying pain. It first produces a stimulating action, which is followed by drowsiness, a disposition to sleep or complete anesthesia, depending on the quantity of the drug used. In poisonous doses a state of exhilaration is well marked at first. This is particularly noticeable in cattle and in horses. The animal becomes much excited, and this stage does not pass into insensibility unless an enormous dose has been given. If the dose is large enough, a second stage sometimes supervenes, in which the symptoms are those of congestion of the brain. The visible membranes have a bluish tint (cyanotic) from interference with the air supply. The breathing is slow, labored, and later stertorous; the pupils of the eyes are very much contracted; the skin dry and warm. Gas accumulates in the stomach, so that tympanites is a prominent symptom. The patient may be aroused by great noise or the infliction of sharp pain, when the breathing becomes more natural. A lapse into the comatose condition takes place when the excitement ceases. Later, there is perfect coma and the patient can no longer be aroused from the insensible condition. The contraction of the pupil becomes more marked, the breathing intermittent and slower, there is perspiration, the pulse more feeble and rapid, till death takes place. Poisoning of cattle with opium or its products rarely goes beyond the stage of excitement, because the quantity of the drug required for the later effects is so great. Seventy-five grains of morphia administered subcutaneously has sufficed merely to excite for 12 hours.
Treatment.—Give strong coffee, 1 to 4 quarts, aromatic spirits of ammonia or carbonate of ammonia. Atropia is the physiological antidote.
STRYCHNIN POISONING.
Strychnin is a very concentrated poison and produces its effect very quickly, usually only a few minutes being necessary if given in sufficient dose and in such a way that it will be at once absorbed. When employed as a medicine, as a rule, minimum doses should be used, as cattle are quite susceptible to its effects and may be killed by the maximum doses given in the common manuals of veterinary medicine. The first noticeable symptom is evidence of unrest or mental excitement; at the same time the muscles over the shoulder and croup may be seen to quiver or twitch, and later there occurs a more or less well-marked convulsion; the head is jerked back, the back arched and leg extended, the eyes drawn. The spasm continues for only a few minutes, when it relaxes and another occurs in a short time. The return is hastened by excitement and in a short time again disappears, continuing to disappear and reappear until death results. As the poisonous effect advances the intervals between the spasms become shorter and less marked and the spasms more severe until the animal dies in violent struggles.
Treatment.—The best method is to put the patient under the influence of chloral, chloroform, or ether, and keep it there continuously until the effect of the poison has passed off. Alcohol may be given in large doses.
ACONITE POISONING.
In recent years tincture of aconite has become a popular stable remedy. If an animal is ailing, aconite is given whether indicated or not. Fortunately the dose used is generally small, and for this reason the damage done is much less than it would otherwise be. Aconite is one of the most deadly poisons known. It produces paralysis of motion and sensation, depresses the heart's action, and causes death by paralysis of respiration. In large doses it causes profuse salivation, champing of the jaws, and attempts at swallowing. If not sufficient to cause death, there is impaired appetite with more or less nausea for some time after. In poisonous doses it causes the animal to tremble violently, to lose power to support itself, and brings on slight convulsions, with perspiration. The pulse is depressed, irregular, and afterwards intermittent.
Treatment.—The chemical antidote is tannic acid, which forms an insoluble compound with the aconitin. The depressing effect on the heart should be counteracted by the use of ammonia, digitalis, alcohol, camphor, or other diffusible stimulants, which have a physiological effect opposite to aconite.
POISONOUS PLANTS.
An important group of poisons may be classed under this head. In most cases it is poison naturally belonging in the plant; in other cases the poisonous principle is developed in what would otherwise be harmless plants as a plant disease, or as a fermentation or putrefaction due to bacterial growth and observed in forage, grain, or meal that has become heated, damaged, or "spoilt."