A comparison is again forced upon us, and we have to lament that as horse doctors our opportunities of combating fatal doses of drugs are very much fewer than those of a medical man. Our patients do not commit suicide, or drink carbolic acid by mistake, and seldom indeed do they get drenched with a poisonous liniment intended for outward application. The mistake is seldom discovered in time when accidental poisoning takes place in horses, and the wilful poisoner has less to fear from the dying depositions of the patient, who can only tell his wrongs by symptoms which may be difficult to distinguish from those of disease otherwise induced. For a variety of reasons the veterinarian has not the same chances of counteracting poisonous doses as the medical man. The human patient can tell his attendant the mistake, and the most suitable treatment may be instantly adopted, while the veterinary surgeon has to wait for the effects before he can ascertain the possible cause.
In nearly all cases the poison is taken into the stomach, and thence passes into the circulation. If we are fortunate enough to be early on the scene we may employ a stomach-pump and evacuate the contents of the organ, in the hope of removing the remaining unappropriated poison therein contained. As such an instrument is not likely to be found in possession of the ordinary horse-owner, it is the more necessary to seek the aid of a qualified veterinary surgeon.
Again, we are at the disadvantage in regard to this animal that we cannot freely excite vomition, as in the dog or cat, so that it nearly always happens in cases of poisoning that reliance must be placed upon chemical or physiological antidotes, and such general measures as may be indicated in order to combat particular conditions.
Since we can scarcely hope to evacuate the contents of the stomach either by a pump or vomition, we have usually to begin the treatment by an effort to arrest the action of the toxic agent upon the walls of the stomach. If poisoning is due to an acid irritant, copious draughts of alkaline bicarbonates are administered, those of potash, soda, magnesia, and lime being most suitable; and in the absence of such pharmaceutical products we may give chalk or whiting, or the scrapings of whitewashed ceilings or walls. Where caustic alkalies have produced the mischief, we resort to dilute acids, as vinegar or lime-juice in small but oft-repeated doses. In addition to those agents calculated to neutralize chemically acids or alkalies, we administer copious draughts of bland fluids in the shape of milk, linseed-tea, whipped eggs, oil, butter, gum, barley-water, etc. While these measures are calculated to save the mucous membrane and walls of the stomach from destruction by an irritant poison, and retard its effects, they will not influence that which has already entered into the circulation of the blood. We have said that in the case of horses, the poison has usually entered the body by means of the mouth and stomach, but there are other gates by which toxic agents may have gained access. The skin, as has been pointed out in connection with the subject of kidney diseases and local applications, may have been the means by which the body has suffered injury. The deleterious agent may have been absorbed by a wound, or passed into the circulation by subcutaneous injection, while the lungs may have inhaled the poisonous gas of mine or factory.
From the foregoing remarks the importance will be seen of ascertaining, if possible, the actual poison to be dealt with.
Antidotes (antidotos, a remedy) are agents which neutralize and arrest the action of poisons. In the stomach and some portion of the intestinal canal this effect may be counted on where the nature of the poison is known and a suitable antidote soon enough administered. In the case of chemical antidotes, their action on the poison frequently results in its decomposition and the formation of a harmless compound. As an example we may mention white of eggs as forming an insoluble albuminate when given to an animal whose stomach has been the receptacle of an overdose. of bichloride of mercury (corrosive sublimate). Arsenic may be made insoluble in like manner by dosing the poisoned patient with freshly-prepared hydrated peroxide of iron. other chemical antidotes convert destructive poisons into harmless salts, as in the case of sulphuric acid (oil of vitriol), which may be decomposed by an alkaline carbonate producing a harmless sulphate and liberating carbonic acid gas.
Examples of physiological antidotes may be seen in strychnia and chloroform or chloral. The tetanic spasms resulting from the former are allayed by the directly opposite effect upon the spinal cord which the two last-named drugs are so well known to produce.
The veterinarian is at a disadvantage throughout the treatment of poisoning, as he cannot evacuate the stomach of the horse at first, as has been already mentioned, and is further unable to get rid of any new compounds formed by the administration of antidotes; they must pass through the intestinal canal. He cannot provoke vomition, and repeated washings of the stomach are scarcely practicable, except in a few instances and under specially favourable circumstances.
In addition to the use of antidotes there are other aids to restoration from the shock and particular symptoms resulting from poisoning: suitable hygienic conditions, fresh air, cold douches, friction to the skin, bandaging and clothing, bedding and protection of the patient from his own violence by bolsters of straw, and the usual methods of restraint. In a case of narcotic poison it may be necessary to rouse the animal to muscular effort and compel him to walk about.
Suitable treatment in cases of poisoning by each of the chief toxic agents known to affect horses will be found briefly stated farther on in this chapter.
On the question of ptomaine poisoning in horses we have no experience as yet, but disease and death from the ingestion of food and water in certain unwholesome conditions are by no means rare events.