Diagnosis: This may be based mainly on the prevalence of the disease in the district, or the fact that the victim has come from a long railway journey with risks of exposure, or has stood by a horse just arrived; on the prompt loss of appetite and sudden and extreme rise of temperature, without notable lung lesions; on the deep brownish yellow discoloration of the visible mucosæ, especially that of the eye, and on the yellow discharge from the nose, the tardiness with which successive cases follow each other comparatively to influenza, and the absence in large measure of the early extreme prostration of that affection. (See table under influenza).
Prognosis varies with the progress of an epizoötic, and the youth and susceptibility of the animal together with the favorable or unfavorable conditions of life. The death rate is usually high at the outset when the more susceptible animals are attacked, and for the same reason, in the young that have not been previously exposed. Old and debilitated animals with broken down constitutions suffer severely, and bad hygiene contributes much to the mortality. The deaths vary from one to twenty per cent. But short of death, permanent injury follows in a number of cases. Encysted sequestra remain in the lungs for months and when liquefied and absorbed, leave fibroid masses in place of healthy lung tissue. The fibrous organization of peribronchial exudates, impairs respiration, and the same is true of the fibrous development of false membrane. Thus the horse is left permanently broken-winded or short-winded, or from interference with the recurrent laryngeal nerve, laryngeal hemiplegia (roaring) ensues. In still other cases permanent adhesions of the pericardium, or insufficiency of the cardiac valves, or disease and distortion of joints or tendons, or nervous, hepatic or renal degenerations destroy or seriously impair the value.
Treatment. Hygienic measures are of prime importance in treatment. A dry, clean box stall with pure air, and genial warmth (60°–70° F.)—in warm summer weather outdoor air—must be secured. In cold weather a sunny outlook, and clothing—blanket, bandages, and it may be a hood—to counteract any sensation of chill. Tepid drinks, pure water changed often, linseed tea, barley water, are of importance in allaying thirst, lowering temperature and favoring elimination. Absolute rest is all essential. Keeping at work after the onset of the disease is nearly equivalent to signing the patient’s death warrant.
The high temperature at the outset of the disease seems to demand antipyretics, and in times past, in Southern Europe especially, bleeding was a constant resort. But even under favorable conditions this does not lower the temperature more than 1.5° F., and the resulting debility is such that it has been long discarded in Germany, England and America. In cases of acute extensive pulmonary congestion it is helpful in relieving the vascular tension on the lungs and allowing the tissues to better reassert their natural functions, in antagonism with invading microbes and their poisons, but even this action is transient, and when it saves life it is probably only by tiding over safely a very transient and urgent danger.
The same decline of temperature can usually be secured by injections of cool water into the rectum, and with the added advantage that this relaxes the bowels, and removes dried irritant masses from the rectum and floating colon.
As in other pneumonias the application of cold to the skin is liable to bring on a chill unless the temperature is very high. A safer and hardly less effective method is to apply around the chest a thin blanket or sheet wrung out of tepid water and cover it closely with dry blankets holding these close to the skin by elastic circingles. No part of the damp compress must be allowed to remain exposed to the air under pain of causing chill. Damp cotton wool applied next the skin tends to maintain its contact by its own elasticity, so that it requires less care in the elastic dry covering. This moist warmth draws a free circulation of blood to the skin, so that it is cooled and sent back internally to cool the burning fever, without sensation of chill. The abstraction of this large mass of blood to the skin, acts like bleeding in diminishing the blood tension in the chest and allowing the resumption of the normal vaso-motor and nutritive functions without the dangers of venesection. The soothing action on the skin, soothes by sympathy the infected and inflamed tissues.
A steam or hot air bath may serve a similar purpose. Conjoined with an aloetic laxative and aconite, I have seen this reduce the temperature from 104.5° F. to 102.7° F. at the next taking 18 hours later. It only once again reached 103° F. in the subsequent course of the disease.
To secure diaphoresis, warm mashes or gruels may be freely used. Alcoholic drinks have been freely used (the weaker wines 1 to 2 qts., sherry, brandy, whisky ½ to 1 pint), camphorated spirit (2–3 drs.) subcutem, ipecacuan (1 oz.), tartar emetic (2 drs.), liquor of acetate of ammonia (4 ozs.), pilocarpin (2 grs. subcutem). If the alcoholic liquors produce a free circulation and glow in the skin, better still if diaphoresis, they are useful antithermics, but, if they fail in this, they may do harm by reducing the vital activities of the leucocytes, and their power of resistance. Trasbot has had uniformly unfortunate results with alcohol in large doses. The same objection attaches to tartar emetic and other depressant diaphoretics, though valuable if free diaphoresis is secured.
Constipation may be met by cold water injections, calomel (½ to 1 dr.), pilocarpin (3 grs.), eserine (1½ gr.), sodium sulphate or other agent graduated to requirement.
An expectorant and alkaline diuretic action may be obtained from potassium iodide (1–2 drs.), ammonium chloride (2 drs.), or ammonium acetate. These not only liquefy the exudate, and facilitate expectoration, but secure elimination of toxins, ptomaines and waste products from the blood and system. The iodide is besides somewhat antiseptic.