Bronchitis is an inflamed condition of the mucous membrane lining the bronchial tubes.
It may occur as a primary disorder in which the larger bronchi are chiefly involved, or it may follow upon or complicate other diseases. Two forms of the malady are recognized - one sharp and of brief duration, known as acute bronchitis, and the other less severe but protracted, termed chronic.
The predisposing causes are weakness, old age, and damp, cold stables. A previous attack and the exhausting influence of other diseases also increase the liability to a second seizure. Young horses in close stables are more subject to it than others, if we except the worn-out and exhausted. The disease may also be excited by the accidental introduction of medicinal agents into the air-passages while administering draughts, exposure to easterly or north-easterly winds after exertion or fatigue, or it may complicate an attack of influenza or strangles, or arise out of an extension of inflammation from the larynx.
As a rule, but with notable exceptions, bronchitis commences with shivering and the symptoms of a common cold; the first thing noted may be a cough and a rattling sound in breathing that in very marked cases can be heard at some distance. The breathing is somewhat quickened, the temperature raised, the appetite indifferent, and a general listlessness is observed as well as disinclination to movement. The pulse is increased in number and diminished in force, the ears and legs vary in temperature, being sometimes cold, sometimes warm. Thirst, too, is often noticed in the commencement of the disease. With the progress of the malady the cough occurs in paroxysms at frequent short intervals, and gives rise to very great distress. When the larger bronchi are chiefly affected it is louder and harsher than is the case when the small ramifications of the tubes become involved. Auscultation is here of much assistance, as by placing the ear on the chest at various points the peculiar sounds emitted will afford information as to the state and progress of the disease. Where the large bronchi are only or chiefly affected, a coarse, rough, or rattling sound will be heard plainly in the front and upper part of the chest; but if the smaller tubes are affected it may also be detected in a modified form by listening behind the shoulder-blade. Here the sound emitted is harsh as compared with normal breathing, and mixed up with it is a coarse or fine crepitation or crackling. The loud, harsh cough presently gives way to a softer one, attended with more or less copious expectoration of mucus, which varies considerably in thickness and tenacity. In these circumstances the chest sounds are quite altered, and the ear detects bubbling and wheezing in the tubes as the air passes through the accumulated matter within them. The patient's prospects of recovery would appear to depend largely upon the viscidity or otherwise of this matter and its possibility of removal.
It is important that remedial measures should be applied early, but too often the disease has gained a firm hold of the animal before professional assistance is called in or the gravity of the case is recognized. The severity of an attack may be mitigated by bold doses of anodynes, as chloral and iodide of potassium, with stimulants; but the disease, when fully established, cannot be cut short by any drastic measures, and the symptoms must be combated, the animal's strength maintained, and his general comfort attended to. The temperature of the stable should be kept up to about 55° Fahr., and outside it a convenient place may be chosen to keep water boiling so that a pail or two of hot water may be brought into the stable to keep the air moist. The legs should be bandaged and the body warmly, but not heavily, clothed, a hood forming part of the suit worn.
If the throat shows signs of soreness, counter-irritation should be applied to it and along the front of the neck to the breast, and if the chest trouble is severe, an application of turpentine liniment to the chest-walls will be desirable. Mustard should not be chosen for this purpose, as the pungent, irritating vapour given off from it while on the skin provokes coughing and tends to add to existing distress.
Although we cannot induce the horse to expectorate in the ordinary sense of the word, yet we adopt those agents known as expectorants to facilitate the removal of mucus from the tubes, where its presence is causing so much annoyance. Electuaries of belladonna, in combination with camphor and ipecacuanha, or tartarized antimony, will be preferred, and especially where sore throat precludes the administration of draughts; but if these cannot be given without distress to the patient, other remedies of a nature too volatile to enter into an electuary may be chosen. Of these, compound tincture of camphor (paregoric elixir), chlorodyne, rather, nitrous rather, carbonate of ammonia, and tincture of squills are among those recommended; while the drinking water may be chosen as the vehicle for such salts as chlorate or nitrate of potash, and the bicarbonates of potash and soda.
Inhalation of steam, or rather, we should say, the vapour of hot water, usually affords relief, and may be made more potent by the admixture of a small amount of friars' balsam, camphor, or eucalyptus oil. These may be mixed with hot bran in a nose-bag, which should not be left on, but used while an attendant is standing by for a few minutes at a time only. With an abatement of the more distressing symptoms the cough in some cases proves obstinate and threatens to become chronic. Medicines may in such cases be advantageously administered in the form of bolus, and be composed of tar, powdered squills, opium and gum ammoniacum, or for opium may be substituted some other anodyne if it has already been given for some time in the course of the attack.
If during the early days of the disease the bowels are constipated as a result of the febrile state, they may be regulated by soft food and a few spoonfuls of linseed-oil given with it from day to day in preference to an aperient dose of medicine. Some glycerine may be introduced into the bowel, or soap and warm water enemata employed. The extreme debility that follows a severe attack may in some instances account for the persistency of the cough, and tonic treatment is then called for.
A fresh-made infusion of gentian, with small closes of carbonate of ammonia or alcoholic stimulants, is worth trial. Rather large doses of quinine, with nux vomica, give just the necessary fillip sometimes when convalescence is protracted. A considerable period of time should be allowed, with gentle and steadily increasing daily exercise, before the animal is allowed to return to his ordinary work, and the greatest care should be observed against exposure to wet or cold easterly winds.