Preventive Treatment.—The subject of preventive medicine becomes more important as our knowledge of the cause of disease advances. A knowledge of feeds, methods of feeding, care, sanitation and the use of such biological products as bacterins, vaccines and protective serums is of the greatest importance to the farmer and veterinarian. We are beginning to realize that one of the most important secrets of profitable and successful stock raising is the prevention of disease; that the agricultural colleges are doing a great work in helping to teach farmers that there are right and wrong methods of feeding and caring for animals; that the practice of sanitation in caring for animals is the cheapest method of treating disease; and that it is advisable to practise radical methods of control, when necessary, in order to rid the herd of an infectious disease.

The ration fed and the method of feeding are not only important in considering the causes of diseases of the digestive tract, but diseases of other organs as well. The feeding of an excessive, or insufficient quantity of feed, or a ration that is too concentrated, bulky and innutritious, poor in quality, or spoiled may produce disease.

An impure water supply is a common cause of disease. A deep well that is closed in properly and does not permit of contamination from filth, does not insure a clean water supply if the trough or tank is not kept clean.

Farm Buildings.—If stockmen would make a more careful study of the kind of farm buildings most suitable to their needs, the selection of the location, the proportions, the arrangement of the interior and the lighting and ventilation, there would be a great saving in losses from disease, and the cost of building in many cases would be lessened. Your neighbor's building that you have taken for your model may not be suitable for your needs. It may be more expensive than your financial condition permits. It may be poorly lighted and ventilated and not suited to the site that you have selected.

Biological Products.—There are a number of biological products that may be used in the prevention and control of disease. Some of these products, such as tuberculin and malein, enable the owner to rid his herds of tubercular cows and glandered horses before these diseases have become far enough advanced to be recognized by the visible symptoms alone. Black leg, anthrax and hog-cholera vaccines are valuable agents in the control of disease. In the treatment of fistula and infectious abortion, bacterins may be used. There are many other germ diseases and infections for which vaccines and bacterins may be used. However, we must not depend wholly on these agents in the control of disease. We must possess a knowledge of the manner in which the infection is spread, for without this knowledge we would be unable to prevent its dissemination over a wide area.

Medicinal Treatment.—The average stockman or veterinarian is more familiar with the treatment of disease with drugs than he is with the preventive measures just described. This statement does not imply that a knowledge of medicinal therapeutics is not of the greatest importance in the treatment of disease. The ultimate object of all drugs is both to prevent and cure disease, but the injudicious use of a drug does neither. A discussion of this subject cannot be entered into here, and because of its largeness it is not advisable to discuss it further than a brief summary of the methods of administering drugs.

Administration of Drugs.—Drugs may be administered by the following channels: by way of the mouth, in the feed or as a drench; by injecting into the tissues beneath the skin or hypodermically; by rubbing into the skin; by the air passages and the lungs; and by injecting into the rectum.

If the animal is not too sick to eat and the drug does not possess an unpleasant taste, it may be given with the feed. If soluble, it may be given with the drinking water, or in any case, it may be mixed with ground feed if this method is to be preferred. In all cases the medicine must be well mixed with the feed. This is especially important if there are a number of animals to be treated, as there is more certainty of each animal getting the proper dose and the danger of overdosing is avoided. If the young animal is nursing the mother, we can take advantage of certain drugs being eliminated in the mother's milk and administer the drug to the mother.

[Illustration: FIG. 6.—A good kind of a dose syringe.]

DRENCHES.—In the larger animals a bulky drench is sometimes difficult to administer, and we should, in all cases, count on a portion being wasted.

Horses are sometimes difficult to drench, and it may be advisable to confine the horse in some way. Small drenches can readily be given with a syringe (Fig. 6) or a small bottle. In giving bulky drenches it is most convenient to use a long-necked, heavy glass bottle. The horse should be backed into a narrow stall and the head elevated by placing a loop in the end of a small rope over the upper jaw, passing the rope back of the nose piece on the halter and throwing it over a beam, and raising the head until the mouth is slightly higher than the throat. If the horse refuses to swallow, a tablespoonful of clean water may be dropped into the nostril. This forces it to swallow. A drench should never be given through the nose, as it may pass into the air passages and cause a fatal inflammation of the lungs.

Cattle can be easily drenched by taking hold of the nostrils with the fingers, or snapping a bull ring into the partition between the nostrils and elevating the head.

Sheep may be drenched either in the standing position, or when thrown on the haunches and held between the knees. Care should be exercised in giving irritating drenches to sheep, especially if the drench be bulky.

A herd of hogs may be quickly and easily drenched if they are confined in a small pen, and the loop of a small rope placed around the snout, well back toward the corners of the mouth. A small metal dose syringe should be used. If the drench is bulky and the hog difficult to hold, it may be necessary to elevate the head and raise the forefeet from the ground. The drench should not be given until the hog is quiet and well under control, as there is some danger of the medicine passing into the air passages and doing harm. It may be necessary to mark the hogs that have been drenched with a daub of paint, or in some other manner in order to be able to distinguish them from the untreated animals.

The administration of drugs enclosed in a gelatin capsule, or mixing them with syrup, honey or linseed oil, and rolling the mass into the form of a cylinder is commonly practised. The capsule or ball may then be shot into the pharynx with a balling gun. A ball may also be given to the larger animals by carrying it into the back part of the mouth with the hand, and placing it on the back part of the tongue. In the horse this method of administration requires some practice. The tongue must be pulled well forward, the head held up, and the tongue released as soon as the ball is placed on the tongue, so that it may pass back into the pharynx.

The administration of drugs by injecting beneath the skin (Fig. 7) is suitable when the drug is non-irritating and the dose is small. Drugs administered in this way act promptly and energetically. The alkaloid or active principle of the drug is commonly used. A fold of the skin is picked up with the fingers and the needle is quickly introduced, care being taken not to prick or scratch the muscular tissue, as this causes some pain and makes the animal restless. In order to avoid abscess formation at the point of injection, the skin should be cleansed with a disinfectant and the syringe and needle sterilized before using.

[Illustration: FIG. 7.—Hypodermic syringes.]

Drugs are not absorbed through the unbroken skin, but when applied with friction, or when the outer layer is removed by blistering, absorption may take place. Liniments, blisters and poultices are the preparations used.

Volatile drugs, such as chloroform and ether, are absorbed quickly by the enormous vascular surface of the lungs. This class of drugs is administered for the purpose of producing general anaesthesia. Anaesthetics are indispensable in many surgical operations.

The administration of a drug in the form of medicated steam is quite useful in combating some respiratory diseases. In steaming large animals a pail about half full of boiling-hot water to which has been added about an ounce of coal-tar disinfectant, or whatever drug is required, is held within about one foot of the animal's nostrils. It is usually advisable to throw a light cover over the head and pail in order to direct the steam toward the nostrils. Dogs can be placed on a cane-seated chair and a pail or pan of boiling-hot water placed under it, and a sheet thrown over all.

Drugs are administered by way of the rectum when the animal can not be drenched, or the drug can not be given in any other way and when a local action is desired. An enema or clyster is a fluid injection into the rectum and is employed for the following purposes: to accelerate the action of a purgative; to stimulate the peristaltic movement of the intestines; to kill intestinal parasites; to reduce body temperature; to administer medicine; and to supply the animal with food. An enema may be administered by allowing water to gravitate into the rectum from a height of two or three feet or by using an injection pump. In the larger animals several feet of heavy walled rubber tubing carrying a straight nozzle at one end should be used. In administering an enema, the rectum should be emptied out with the hand and the nozzle of the syringe carried as far forward as possible. The operator should be careful not to irritate or tear the wall of the rectum.

Size of the Dose.—The doses recommended in the treatment of the different diseases, unless otherwise stated, are for mature animals. The dose for a colt one year of age is about one-third the quantity given the adult, two years of age one-half, and three years of age two-thirds. In well-matured colts a larger dose may be given. In cattle, the doses recommended are about the same. In the smaller animals the size of the dose may be based on the development and age of the animal. When the drug is administered at short intervals or repeated, the size of the dose should be reduced. The physiological action of some drugs may be changed by varying the size of the dose.

QUESTIONS

1. Give a general description of preventive treatment.

2. By what channels may drugs be administered?

3. How are drenches administered?

4. How are solid drugs administered?

5. What kind of drugs are administered hypodermically?

6. What is an enema?

7. What proportion of the dose of a drug recommended for the adult may be given to immature animals?