By the rectum.—Medicines are usually administered by the rectum for the purpose of controlling the bowels and for the treatment of local diseases. Sometimes, however, medicines that have a general effect are given in this way when, for any reason, it is not possible or convenient to give them through the mouth. Only drugs that are readily absorbed should be given per rectum for a general effect and in somewhat larger dose or more frequently than when given by the mouth. Such stimulants as ether, alcohol, or the aromatic spirits of ammonia, diluted with from four to six times their bulk of warm water, may be used in this way.
Rectal injections, or enemata, are used in the treatment of constipation. If it is the purpose of the injection to soften hardened fecal masses, the water should be comfortably warm and may have a little clean soap in it. If it is the purpose of the injection to stimulate sluggish bowels to contraction, the water may be cold.
In giving rectal injections a rectal syringe may be used, or, better, a piece of one-half to three-quarter inch rubber hose 5 feet long with a tin funnel attached to one end. The hose is soaped or oiled and introduced slowly and gently into the rectum 2 or 3 feet. The fluid is then slowly poured into the funnel and allowed to gravitate into the rectum. The same apparatus may be used for feeding by the rectum.
By the vagina.—Medicines are inserted into the vagina, and through the vagina into the womb, in a manner similar to that of rectal administration. Most of the medication made use of in this way is for the local treatment of these organs. Following calving, during outbreaks of abortion, and in an infectious disease of the vagina, such injections become necessary.
By the udder.—Injections into the udder are now regularly made in the treatment of parturient paresis (milk fever). For this purpose a 1 per cent solution of iodid of potassium is commonly employed, although some other solutions and oxygen gas are also used. In making this injection so many precautions are necessary in relation to the sterilization of the apparatus and the teats and skin that this work should be left to a skilled veterinarian. The introduction of even a minute quantity of infectious dirt may cause the loss of the udder. For making this injection one may use one of the prepared sets of apparatus or a milking tube and funnel connected by a piece of small rubber hose. The apparatus should be boiled and kept wrapped in a clean towel until needed. The udder and teats and the hands of the operator must be well disinfected, and the solution must be freshly made with recently boiled water kept in a sterile bottle. The udder should be emptied of milk before the injection is made. After all these precautions have been observed the milking tube may be inserted and through it one-half pint of solution introduced by gravity air pressure or by syringe. There is practically no danger in this mode of treatment if it is properly carried out.
Injections into the udder are sometimes made in the treatment of garget, but so far with indifferent success.
By the nostrils.—An animal may be caused to inhale medicine in the form of gas or vapor or to snuff up a fine powder. Sometimes, for the purpose of local treatment, fluids are injected into the nose.
A medicine inhaled may have either a local or a general effect.
Medicated steam, carrying the volatile products of compound cresol solution, carbolic acid, balsam of Peru, compound tincture of benzoin, tincture of iodin, etc., may be liberated beneath the nostrils of a cow so that she must inhale these soothing vapors; but such treatment is not so common for cattle as for horses. In producing general anesthesia, or insensibility to pain, the vapor of chloroform or ether is administered by the nostrils. As a preliminary to this it is necessary to cast and confine the animal. Great care is necessary to avoid complete stoppage of the heart or breathing.
By the trachea.—Medicines are injected into the trachea, or windpipe, in the treatment of some forms of diseases of the lungs, and especially in that form of bronchitis or pneumonia that is caused by lungworms. For this injection a large hypodermic syringe, fitted with a very thick, strong needle, is used. The needle is to be inserted about the middle of the neck and between the cartilaginous rings of the trachea.