EQUINE INFLUENZA. ADYNAMIC CATARRHAL FEVER OF SOLIPEDS.
Synonyms. Definition. Historic notes. Equine influenza of 1872–3; its indication of infection. Other evidence: through stables, cars, manure, clothes, coition, inoculation. Bacteriology: streptococci; diplococci; cocco-bacillus, latter pathogenic to rodents, dog, cat, sheep, pig, ox, ass, pigeon, chicken. Inoculations on horse. Present in early stages only. Uncertainty. Accessory causes: chill, electric tension, high barometer, impure air, overwork, poor feeding, season, youth, primary susceptibility, acquired immunity. Incubation 1 to 3 days. Symptoms: Forms: sudden attack, anorexia, profound prostration, weakness, hyperthermia, epiphora, brownish red conjunctiva, pulse, heart beats, catarrhal symptoms, thoracic, pulmonary, pleuritic, cardiac, digestive, urinary, diarrhœal, ophthalmic, nervous, rheumatoid; complications, abortion, laminitis, strangles, contagious pneumonia, cerebro-spinal meningitis, etc. Lesions: inflammation of mucosæ of nose and air passages with blood unaffected; in severe attacks, with heart clots, or later with blood black, diffluent, red globules crenated or dissolved, without viscidity or rouleaux, reddish serum, and hæmatoidin in masses, acid reaction, petechiæ; congestion of mouth, stomach, small intestines or large,—ulcers, tumid follicles, peritoneal effusion, enlarged congested mesenteric glands; liver as if parboiled, with petechiæ and necrosis; spleen large and gorged; kidneys infiltrated, mottled, petechiated, swollen; may be meningeal or ophthalmic congestion; pulmonary lesions, pleural effusions, adhesions, infiltrations, consolidations, infarctions, sequestra. Diagnosis: sudden attack, great numbers attacked, marked prostration, conjunctivitis, great hyperthermia, digestive disorder, evidence of infection. Table comparing croupous and contagious pneumonia and influenza. Prognosis. Mortality low,—high in some epizoötics, in horses kept at work, under bad hygiene. Treatment: good diet and hygiene, rest, shelter, stimulating diuretics and diaphoretics, venesection, antipyretics, alkaline eliminants, inhalants—water medicated, derivatives, collyria, guarded laxatives, antiseptics, cardiac stimulants, nerve sedatives, tonics, transfusion of blood, normal salt solution,—technique. Prevention: quarantine difficult, yet possible; examples, applicability to countries, to districts, lines of restriction.
Synonyms. Epizoötic Catarrh; Catarrhal Fever; Nervous Fever; Epizoötic; Rheumatic Catarrh; Cocotte; Gastro-enteric Epizoötic; Gastro-entero-nephro-hepatitis; Gastro-Conjunctivitis; Gastro-Hepato-meningitis; Entero-pneumo-carditis; Pink eye; Epizoötic Cellulitis; Typhose; Typhoid Fever; Blitz Catarrh; LaGrippe; Septicæmia Hæmorrhagica etc.
Definition. An infectious fever of solipeds, of a specially low or adynamic type, and with a tendency to localization on the respiratory or gastro-intestinal mucosa, on the eyes, lungs, pleura, heart, liver, kidneys, subcutaneous connective tissue, joints, fascia, or nervous system.
This disease was long confounded with the influenza of man and while compelled for the identification of the affection, to retain this name in combination with the qualification equine, yet we would prefer to discard it entirely as conveying the idea that the illness is caused by Pfeiffer’s bacillus, which it is not. The term typhoid fever which is in common use in France, has been selected to convey the impression of its two prominent features of hyperthermia and stupor. But it is open to the same objection for it has been long applied to a specific disease in man having its own bacillus which is not present in the equine influenza. Septicæmia Hæmorrhagica which has been adopted more lately, however correct it may be as indicating the tendency of the local lesions has a generic meaning rather than a specific one, and requires much more qualification to correctly designate the disease. The term adynamic catarrhal fever of solipeds has this recommendation, that it expresses the prostration and debility which is such a marked feature of the disease, its great tendency to become localized on mucous surfaces, and the genus of animals that prove its victims. A better designation is still desirable and may perhaps be reached, when the pathogenic microbe shall be demonstrated beyond question.
Historic Notes. Among catarrhal fevers and epizoötics of early times it is impossible to distinguish this from widespread nasal and bronchial catarrhs, and from contagious pneumonia (brustseuche), yet when the epizoötic attained a sudden and wide extension without any direct climatic cause, the presumption is in favor of the disease now before us. Hints are obtained from Titus Livius of a Sicilian equine epizoötic of this kind 412 B. C. This is corroborated by an account by Hippocrates of a similar outbreak in Greece. Later, Virgil (Georgics), Columella, Absyrtus and Vegetius give similar hints. In 1299 in Seville horses suffered with drooping head, watery eyes, beating flanks and anorexia and 1000 died (Laurentius Rusius). The horses of the French Army in Germany suffered severely in 1648 (Solleysel), horses in England in 1688 (Short, Rutty), again in 1693 (Webster, Short, Foster) and again in 1699 (Webster). In 1712 horses suffered extensively in Europe (Lancisi, Kanold) and in 1727–8 in England and Ireland (Rutty), in 1732–3 (Arbuthnot, Gibson) and again in 1736–7 (Short). Other such equine epizoötics are recorded for Europe in 1729 (Löw), for Ireland in 1746 and 1750–1 (Rutty, Osmer), for Europe and the British Isles in 1760 (Bieset, Rutty, Webster), and again in 1762 (Rutty, Webster) and 1767 (Forster), also in America (Webster), in Europe in 1776 (Fothergill etc.), in Europe and Asia in 1780–2 (Gluge), in England in 1798 (Wilkinson, White), in Europe and England in 1814–15 (Heusinger, Wilkinson, Youatt), in England in 1819, 1823 (Field) and 1827 (Brown), in Europe in 1833 (Prinz, Wilkinson, Hayes, Spooner), 1834 (Hensinger), 1835–6 (Prinz, Friedberger), 1840, 1846, 1851, 1852, 1862, 1870, 1873, 1881, 1883, 1890, 1891, 1892 (Friedberger).
In the United States as in Europe the affection has in the main smoldered in the large cities in ordinary years, to break out without obvious cause, in given years into an advancing epizoötic which sweeps the whole continent. Such were the great outbreaks in Europe in 1881 to 1883, and in America in 1872–3, and 1900 to 1901. The great recrudescence of the disease in North America in 1872–3 was so remarkable in its progress and limitations that it seems desirable to recal its more prominent historic features. The unquestionable demonstration of the microbe of the affection may make such a record superfluous, but until then, and so long as books are published which attribute the disease to the environment, or to the soil, it is not altogether unnecessary.
PROGRESS OF EQUINE INFLUENZA OF 1872–3.
Last week of September, 1872. Toronto, Ontario; (30th) and neighborhood.
First 2 Weeks of October. Barrie, Collingwood, Owen Sound, Guelph, Ont.; St. John, N. B. (13th); Niagara Falls, (11th), N. Y.; Montreal (8), Ottawa (12th), Stratford, Brantford, London, Can.; Buffalo, N. Y. (14th); Detroit, Mich. (13th).
Third Week in October. Goodrich, Kingston, (19th), Ont.; Rochester (18th), Syracuse, Lockport, Canandaigua, Geneva, Albany, (19th), Ogdensburg, (21st), New York, (21st) N. Y.; Bangor, Me.; Port Huron, Mich.
After Third Week in October. Quebec, (28th) Can.; Utica, (29th), Watertown, Oswego, Schenectady, Saratoga Springs, Poughkeepsie (28th), Elmira, Binghamton, (28th), Jamestown, Ithaca, (31st), Port Jervis (29th), Nyack, N. Y., (30th); Revere, (22d); Springfield, (23d), Worcester, (27th), Fall River, New Bedford, Mass.; Waterbury, (27th), Norwich, (23d), New Haven, Hartford, Conn.; Providence, (23d), Newport, R. I.; Burlington, (26th), St. Albans, Vt.; Concord, Nashua, Portsmouth, (23d), N. H.; Bath, (28th), Portland, Me.; Philadelphia, (26th), Harrisburg, Lancaster, York, Erie, Corry, Titusville, (28th), Pittsburg, (29th), Pa.; Baltimore, (25th), Md.; Washington, D. C., (28th); Norfolk, (31st), Richmond, Va.; Cleveland, O.; Chicago, (29th) Ill.
First Week of November. Kingston, N. Y., (1st); Rutland, Vt., (3d); Meadville, (2d), Pottsville, Williamsport, (6th), Reading, Easton, Bethlehem, Pa.; Trenton, N. J., (2d); Wilmington, Del., (6th); Jackson, Mich., (7th); Milwaukee, Wis.; Raleigh, N. C.; Charleston, S. C., (4th).
Second Week in November. Scranton, Pa., (13th); Lynchburg, Va., (11th); Wheeling, (13th), Parkersburg, W. Va.; Dayton, Sandusky, Toledo, O.; Adrian, Kalamazoo, (9th), Grand Haven, Mich. (8th); Davenport, Ia., (14th); Janesville, Green Bay, Wis.; Louisville, Ky., (9th); Wilmington, N. C., (12th); Columbia, S.C.; Savannah, Ga.
Third Week in November. Steubenville, (15th), Columbus, (16th), Zanesville, (16th), Springfield, O.; Indianapolis, (17th), Fort Wayne, Lafayette, Evansville, (21st), Ind.; Bloomington, Galena, (21st), Ill.; Dubuque, Iowa City, Ia.; Madison, Fond du Lac, Wis.; St. Paul, Minn.; Memphis, Nashville, Chatanooga, Tenn.; Augusta, Atlanta, Ga.; Helena, Fort Smith, Ark.; Havana, Cuba, (20th).
In November after third Week. Terre Haute, Madison, Ind.; Peoria, Galesburg, Ill.; Keokuk, Muscatine, Des Moines, Ia.; Paducah, Ky.; Knoxville, Tenn.; Charlotte, New Berne, N.C.; Macon, Rome, Columbus, Ga.; Jacksonville, Lake City, Fla.; Mobile, Montgomery, Selma, Ala.; Natchez, Vicksburg, Miss.; New Orleans, (25th), La.; Galveston, (29th), Houston, (28th), Tex.; Little Rock, Ark.
First week in December. Cairo, Ill.; Lincoln, Omaha, Nebraska City, Neb.; Yankton, (5th), Vermilion, Dak.; Tallahassee, Fla.; Camden, Ark.; St. Louis, Kansas City, Mo.
Second Week in December. Quincy, Ill. (8th); Shreveport, La.; Hanibal, Mo.; Fort Scott, Lawrence, Leavenworth, Topeka, Kan.
December after the Second Week. Denver, Central City, Col.; Cienfuegos, Cuba.
January 1873. San Antonio (3d) Tex.; Cheyenne, Wyo.; Cimarron, (1st week), Elizabeth City (2d week), Alberquerque (4th week), N. M.; Salt Lake City, (2d week), Corrinne (3d week), Utah; Santiago, Cuba.
February. Brownsville (3d week) Tex.; Winnemucca, Nev.; Monterey (1st week), Mex.
March. Prescott (1st week), Tucson (2d week), Yuma (4th week) Ariz.; Boise City, (3d week), Ida.; Helena (4th week) Mont.; Virginia City, (1st week), Nev.; Carson City, Nev., Santa Barbara, Visalia, Cal.; Guaymas, Mazatlau, Manzanillo, Mex.
April. San Diego (1st week), Mariposa, Stockton, San José, Oakland, Sacramento, Marysville and Shasta (2d week), San Francisco, Vallejo, Nevada City and Weaverville (3d week), and Lava Beds, Cal. (4th week); Baker City (2d week), Jacksonville, Ore. (4th week); Walla Walla, Wash. (4th week); Acapulco (1st week), Mex.
May. Eugene City, (3d week), Dallas and Portland, Ore. (4th week); Olympia, Wash.
June. Seattle, Wash. (3d week).
July. Guatemala City, Guatemala (2d week), Victoria, B. C.
August. La Union, San Salvador (1st).
Among the deductions from this record are:
1. The affection advanced gradually from Toronto over the whole continent of North America, where horses are kept, taking full ten months to accomplish this. Nothing checked its advance, over lowland and highland, swamp and arid land, in summer as in winter, with a temperature at 0° or at 100° F., in country pasture or in city street or stable, idle or overworked, on all kinds of soils and geological formations, under all successive conditions of meteoric and terrestrial electricity, in all conditions of the air—pure, impure, dense, light, moist and dry. No one condition of the environment operating on the animal system, can be conceived of that could advance as this disease did from place to place in regular sequence for this length of time.
2d. The rapidity of its progress was manifestly subordinate to the activity of the movement of the equine races from points already infected. Its most rapid advance was along the lines of railway while the back districts shut out from railway traffic were much later in being invaded. The larger cities situated on the through railroad routes suffered earlier than the smaller places on the same lines. The outbreak was several days earlier in Montreal than in the nearer and smaller cities of Kingston, Ottawa, Belleville, Port Hope, Peterboro, Stratford, Brantford, Guelph, London and Owen Sound. The important port of St. John, N. B., suffered two weeks earlier than Quebec. Along the N. Y. Central and Erie Railways etc., Boston and New York suffered nearly a week earlier than Utica, Poughkeepsie, Binghampton, Elmira, and Jamestown, while the smaller places like Kingston, Nyack, Ithaca, etc., were later still. In Baltimore the disease was seen a day earlier than in Philadelphia, and in these cities and Washington over a fortnight before it was seen in Scranton, Pa. So it was almost everywhere and in these large cities the outbreak could in nearly every case be traced to horses just arrived from a pre-existing centre of infection. In Detroit, Syracuse and Chicago it spread first in stables that had just received Canadian horses, in Ithaca in one which had received horses from an infected centre in Northern New York and in Pittsburgh and Washington in stables that had just admitted horses from infected New York.
3d. It advanced with much greater rapidity eastward than westward, being in the line of greatest horse traffic, the animals being mainly raised and fitted in the West and shipped in large numbers to the great cities near the Atlantic seaboard.
4th. In the absence of this active railway traffic In horses, the advance was most rapid through other lines. In Pa., in a number of valleys opening to the south, the disease reversed its general direction, and extended northward up these valleys. In Lehigh Co., Pa., it followed the course of the canal, being carried by horses and mules employed on the towpath. In Davidson and Sumner Cos., Tenn., it followed the track of a circus which came through an infected locality. It reached the Pacific coast at Santa Barbara (not at the railway terminus at San Francisco) having followed a mule stage route in the absence of an active, westward progress of horses by rail.
5th. The affection failed to overstep any serious gap over which there was no movement of equine animals. It prevailed in Victoria, B. C., in July, but, owing to a strict quarantine on horses and mules, it failed to reach Vancouver Island. It ravaged New Brunswick and Nova Scotia in November but failed to reach Prince Edward Island which was then ice bound and shut off from all traffic with the mainland. It ravaged Cuba to which it was brought by American horses landed at Havana, but no other West Indian island was attacked. Its southward course was finally arrested at Central America, where horses are few and horse traffic nearly unknown.
Every fact in connection with its eruption and progress agrees perfectly with the hypothesis of transmission by contagion alone, and taken altogether the history excludes all other causes from being anything more than accessory. Before the days of modern bacteriology we had ample proof that glanders, rabies, sheeppox, lung plague, and Rinderpest were due to contagion alone as an essential cause, and so now we have the same evidence concerning equine influenza.
Other testimonies to Contagion. Trasbot says the virulence is “almost equal to that of Rinderpest or aphthous fever,” and adds “all practitioners have become assured that the bringing of an affected animal into a stable constantly introduces the malady to the others.” Cadeac says “the diseased or infected animals are the main channel of propagation of the malady” and again the disease is “essentially infectious.” Friedberger and Fröhner are more definite—“influenza which is as highly infectious as any other disease can be produced only by infection.” Cadeac implies nearly as much in saying: “in all the epizoötics that have invaded Paris, the disease has been carried into the four quarters of France by horses bought in this city. In most regiments the malady shows itself after the arrival of horses from remounts where it was prevailing. At Sibourne it is through horses from St. Jean d’Angely. At Lyons it is by a horse from Cæn. At Bourges the source was not traced but it spread from the garrison to the whole surrounding country. The Omnibus stables in the Rue d’Ulm were invaded when a horse was introduced from Clichy where influenza raged.”
Stables are fruitful sources of infection hence dealers’ horses and horses travelling from place to place have long been objects of just suspicion (Trasbot, etc.).
Cars are often infected, and spread the disease widely. (Poucet, Salle, Trasbot, etc.).
Manure is especially dangerous. Trasbot gives a number of cases of the infection of farms, by the manure taken from the Alfort Veterinary College, and other infected stables in Paris. Friedberger conveyed the disease experimentally in the manure.
The conveyance of the virus on the clothes of attendants has been alleged by Friedberger and Fröhner, and considering that it has been noted to pass over intervals of about half a mile without the intervention of any horse, it must have been wafted on the air, or conveyed on the surface of man or non-equine beast.
Jensen and Clark allege that the contagium may be conveyed to mares by coition, for months after the stallion has shown all outward signs of recovery. This would be entirely in keeping with the analogous fact in swine plague.
Inoculation. Experimental inoculations have transmitted the disease with difficulty and uncertainty. Those of Hertwig, Nocard, Arloing, Labat, Friedberger, Trasbot, Pasteur and others came to naught. Even the transfusion of the blood of the sick, proved as harmless as the inoculation of the serous exudate. A probable explanation is found in the extreme diffusibility of the germ of equine influenza, which spreads over a city or county in a few days, attacking practically all equine animals. Inoculation is necessarily made at the time of the prevalence of influenza and at such a time all horses in a wide area are likely to be suffering from the affection. Those that are unaffected and therefore apparently available for experiment, are the immune animals. If they were susceptible the probability is that they would speedily show the disease through infection drawn from another source than the inoculation. If the inoculated animal failed to contract the disease, and yet very shortly afterward became infected by simple exposure, there would be some basis for alleging that inoculation was always inoperative. Dieckerhoff, on the other hand, transmitted the disease to healthy horses by subcutaneous and intravenous inoculation of the blood of the sick, and the same seems to be true of inoculations of the cultures of the cocco-bacillus by Lignieres.
Bacteriology. Our knowledge of the bacteria of equine influenza is as yet very imperfect and uncertain. Galtier and Violet found streptococci and diplococci in the blood and tissues of cases showing intestinal lesions, and held that they were derived from musty fodder. Injections of infusions of such fodder into the trachea of the horse produced broncho-pneumonia, double pleuro-pneumonia, and at times intestinal or meningeal congestion. But there is no proof that the malady so caused, passed with the certainty and rapidity of equine influenza from horse to horse in the same stable.
The cocco-bacillus found by Lignieres in the blood and exudate of the patients has more plausible claims to being the specific germ. This is an ovoid bacterium, somewhat smaller than that of chicken cholera, and like it pigmented at the poles and clear in the central part, a characteristic feature of the group of Pasteurella of Trevisan. This group includes the nonmotile germs of swine plague, the septicæmic pneumo-enteritis of sheep, wildeseuche, and septicæmia of rabbits and chickens, as well as that of fowl cholera; all stain easily in gentian violet and fuchsin, and all cause some form of hemorrhagic septicæmia. The germ is ærobic and grows best in peptonized bouillon to which a little serum has been added. It forms, in peptonized gelatin, round colonies, at first transparent and later opaque or milky, and without liquefaction. The cultures when inoculated subcutaneously proved fatal to Guinea pig, rabbit, rat, mouse, dog, cat, sheep, pig, ox, ass, pigeon and chicken.
Intravenous inoculation on the horse of 1 to 2cc. of the culture kills in a few hours, the temperature having risen to 104° F., the mucosæ acquire a dull brown tint, the eyes are swollen and weeping, enteritic colics appear, the limbs may swell and there may be painful arthritis and jaundice. At the necropsy the blood is black and incoagulable, the muscles as if parboiled, the liver a deep violet, the intestinal mucosa congested, a yellowish or reddish effusion in the pericardium and numerous petechiæ on the serosæ.
Subcutaneous inoculation causes an enormous inflammatory œdema resulting in a sanguinolent abscess, in case the subject survives. There are also hyperthermia (106° F.), dulness, stupor, weakness, staggering, and congested, swollen, weeping eyes.
Intratracheal injection is harmless to the horse.
Lignieres finds his cocco-bacillus in the expectoration at the outset and in the nasal and guttural forms of the disease later, but not in the blood nor lungs after death, as it is then replaced by streptococci, the great reproduction of which is favored by its presence. In ordinary cases of equine influenza it is often impossible to find the cocco-bacillus in the lung or other organs after an illness of 8, 10 or 15 days. (Lignieres).
Lignieres appears to have omitted the obvious test of the infection of other horses in the same stable, from the cases produced by his experimental cultures, so that we must still call for more confirmatory proof. Cadeac, indeed, assures us that cultures of cocco-bacilli taken from cases of equine influenza, are often innocuous. Deadly as the germ cultures of Lignieres prove, they appear to lack that element of extreme infectiousness shown by equine influenza when the susceptible animals come into proximity with the sick.
Accessory Causes. The recognition of the one essential cause in the microbian invasion, need not exclude as accessory factors the many unwholesome conditions which have long been recognized as contributing to the severity of epizoötics. As the seed requires the rich field, the rain and sunshine to bring it to an abundant harvest so the microbe of equine influenza flourishes best where the conditions are most favorable and the antagonisms least.
The chill which comes from a sudden extreme fall of temperature, or the standing in a cold draught when wet or perspiring, lays the system open to this as to other microbian invasions.
The electric tension preceding a thunderstorm, to which many of the lower animals are excessively susceptible equally prepares the system to succumb to the germs. It may here be noted that September 1872, the last days of which witnessed the start of the great epizoötic, had no less than eleven thunderstorms, while in September of the previous year there were but two in the vicinity of Toronto. It is just possible that the great and frequent electric tension, lowered the animal vitality, allowing a violent invasion by the hitherto slumbering germ, and gave to the latter that encreased potency which sent it forth on that year of almost unparalleled epizoötic record.
The high barometer and low dew point similarly affect the animal economy and encrease receptivity to disease. Rain fell at Toronto 16 days in September 1872 and but 8 days in September 1871.
Impurities in the air whether originating in volcanic eruptions, telluric emanations, close, filthy overcrowded buildings or compartments or large collections of decomposing organic matter, impair the animal vigor and lay the system open to a more violent attack. For this among other reasons epizoötics of equine influenza are nearly always more deadly in the closely packed city stables than in the pure country air.
Overwork and poor irregular feeding and watering pave the way for debility, prostration and severe invasion.
Sudden vicissitudes of temperature, which are so common in spring and autumn, associated as they are with the shedding and growth of the coat, materially encrease susceptibility and sometimes determine an encreased severity in the attack.
Youth has its influence, even if it means only that the system that has never before been exposed to the poison, retains all its native susceptibility, and has none of that acquired immunity which comes from a previous exposure to the virus and successful resistance.
Acquired immunity must of course be reckoned with. After a non-fatal attack this is usually to be relied on for several years or even for the rest of the lifetime, yet it varies with the individual animals, and, under the baleful combination of a specially potent germ and strongly conducive accessory causes, it may become worn out in a year. Yet the older horses can always be trusted to show a large measure of this immunity, so that in the absence of extraordinary epizoötics it is mainly the young that suffer, and it is only when a country has had no general invasion for a length of time, or when the germ has acquired an unusual pathogenic potency, or when these two conditions conjoin, that the invasion of the equine population becomes universal, as it virtually was in the United States and Canada in 1872–3. Under other circumstances the germ, temporarily shorn of its power, lingers in city and dealers stables, biding its time until circumstances become more favorable for a new general outbreak.
Immunity largely explains the comparative mildness of the last cases in any particular locality. The more susceptible animals are attacked first and most severely, while the partially immune ones, which for a time resist, throw off the disease with greater readiness. The explanation has been sought in a lessening potency of the germ, but though this may hold true of some cases, it manifestly does not apply when slight lingering cases only are left in one locality, and the disease is advancing over the neighboring state with all its original force and vigor.
Incubation. This appears to vary within certain limits. When during an epizoötic a sick horse is brought into a new locality and stable, other cases usually develope in from one to three days. Trasbot gives examples of one day, Salle, Cadeac and others of two, others claim four, seven and even, exceptionally, fifteen days. One reason for an apparently prolonged incubation may be found in the seclusion of the germs in the alimentary canal, so that they escape only when passed with the fæces. The pathogenic potency of individual germs, and the varying susceptibility of the animals exposed must also be taken into account.
Symptoms. Equine influenza is liable to show a special predilection for a given set of organs in different epizoötics, so that we find descriptions of the different forms as independent types or even separate diseases: as the catarrhal form, thoracic form, abdominal form, bilious form, nervous form, pink eye, infectious cellulitis, and rheumatic influenza. These forms may, however, appear in different subjects in the same epizoötic, and when they are not due to complications, may be looked on as a concentration of the morbid processes on one class of organs rather than another.
Initial pathognomonic symptoms. Certain prominent and striking symptoms are so constantly present in the earlier part of the disease that they may be held as virtually diagnostic. These are the suddenness of attack, the anorexia, the profound early prostration and weakness, the high temperature, the swelling and watering of the eyes, and the specially brownish red coloration of the conjunctiva and other visible mucosæ. The attack may come on with almost lightning rapidity. The animal which yesterday, or it may be but an hour or two ago, appeared to be in the most vigorous health and spirits, is found with pendant head, resting perhaps on the manger, ears drooping, eyelids swollen and half closed, epiphora, conjunctiva of a brownish red or violet, lips loose and drooping, and one or two legs partially flexed, while the body is balanced on the others. The patient is indisposed to move, and when compelled to walk may sway and stagger from nervous and muscular weakness. The arched back, cracking limbs, and their stiff, rigid movement further indicate the suffering in muscles or joints or both. Appetite is greatly impaired or lost, thirst marked, and hyperthermia 102° to 105° or upward. Sneezing, cough or symptoms of some other special localization may be present, but the above occurring in a number of horses at once, without appreciable climatic cause, when one or two new horses have been very recently acquired, or when influenza has been prevailing in the vicinity or in a neighboring place, will usually stamp the nature of the attack.
Cadeac considers the sudden attack, high fever, and profound nervous prostration and stupor as the manifestations of the uncomplicated disease, while the localizations in the lungs, bronchia, pleura, liver, bowels, etc., are indications of complications by germs of other diseases, which find the debilitated influenza system especially open to attack. The fever which always sets in early may be little above the normal in mild cases, and may reach 107° or 108° F. in the more severe ones. It may last thus for five or six days and then rather suddenly descend to near the normal. In other cases it descends a little daily, the lowest temperature for the day being seen in the morning. Shivering is often nonexistent or passes unperceived.
The pulse does not usually encrease in ratio with the temperature. It may be at first only 40 or 50 per minute, though later, and especially with extensive disease of important organs, it may reach 60, 70, 80 or even 100. It usually lacks in firmness and force, even when the heart beats forcibly, being soft, somewhat compressible, and often irregular in successive beats, the weakest corresponding to the last part of the inspiratory act, or when the lungs are full and the heart compressed. The heart impulse behind the left elbow is usually forcible and may show variation in rhythm or even intermissions.
Mild catarrhal symptoms of the nose and throat are usually present, the discharge being at first serous and later muco-purulent. As a rule this is complicated with more or less bronchitis, but this does not indicate anything serious. Acceleration of the breathing, sneezing, and cough are present. Cough may be at first nervous, husky and paroxysmal, but later as the discharge is established it assumes a looser, mucous character. It is liable to be roused by excitement, by drinking cold water, by inhalation of dust, or by giving medicine. In connection with these symptoms there are some indications that the digestive organs are involved. The pharyngeal and submaxillary glands may be swollen and tender. If the subject has been seized just after a full meal, there may be slight tympany, and in any case, the fæces are passed in small balls, a few at a time, hard and with a baked or glistening surface. These may have an unusually strong or heavy odor, and laxatives are liable to act with dangerous energy. The urine is scanty and high colored, sometimes icteric.
In such mild attacks, which constitute the majority, improvement may be noted as early as the fourth day, and a prompt recovery follows.
With extensive thoracic lesions, the symptoms are much more severe and the danger greatly enhanced. These may occur in any patient, but there appears to be a special predisposition in the young and still very susceptible animals, in those crowded together in close, badly aired buildings, in the overworked, poorly fed or in any way debilitated subject, and in horses that have been especially excited and exposed, as by railway travel.
In exceptional cases congestion of the lungs may be so acute as to lead to speedy death, and the objective symptoms do not differ greatly from those of ordinary cases of this condition, if we except the very high temperature in influenza, associated as it is with the fact of the epizoötic prevalence of the disease.
In pneumonic cases the lesions are usually double and have a tendency to develop toward the lower borders of the lungs, just behind the elbow or farther back, and less frequently in the centre of the organ. It may be impossible to detect crepitation, but sounds of distant organs (heart beats, bronchial blowing, intestinal rumbling) are heard with unwonted clearness over the consolidated parts. A mucous râle can usually be detected behind the shoulder blade, along the line of the larger bronchia. Percussion sounds may be indefinite, as the area of consolidated lung is usually small in ratio with the hyperthermia. The area of flatness in ordinary fibrinous pneumonia is usually much greater with a high fever, and if the lesions are on one side only, right or left, it is still more suggestive. The crepitation too in pneumonia is significant. When the pulmonary lesions are extensive by reason of œdema, a marked infiltration may often be noted on the lower surface of the trunk or in the limbs as well.
Pleuritic symptoms may show in the same connection. The breathing becomes more hurried and shorter, friction sound may be heard but it is very transient and soon superseded by an absolute flatness on percussion, rising to a definite horizontal line, representing the boundary of the effusion in the lower third or half of the chest, and usually rising to the same height on both sides. Tenderness of the intercostal spaces may or may not be present. As the disease advances creaking sounds may be heard from the stretching of the consolidated false membranes. The combination of double pleuro-pneumonia constitutes a very fatal type of the disease.
The symptoms of pericarditis and of cardiac disorder usually accompany those of pleurisy. The tumultuous heart beats, often associated with soft, weak or even rapid pulse, and later, a deadening or muffling of heart sounds, as in hydropericardium are characteristic when present. With endocarditis the early tumultuous heart beats, with small weak pulse, irregular and sometimes intermittent, become complicated by a blowing or hissing murmur with the first heart-sound. In such cases clots of blood are liable to form in connection with the valves, and may cause sudden and early death. When the heart is involved the tendency to extensive infiltration of limbs and lower aspect of the trunk is much enhanced. (See diagnosis for table of phenomena in influenza, fibrinous pneumonia and contagious pneumonia respectively).
Symptoms of digestive disorder are usually in evidence. Even in the thoracic forms the mouth is dry, hot, and has an offensive odor; the tongue coated above, has often red margins and tip; it may even be yellowish; the gums may be swollen and dark red or violet especially around the incisors; mastication may be slow and unwilling; the pharynx maybe swollen; the pharyngeal and submaxillary lymph glands may be tumid and tender; and swallowing may be difficult.
Congestions of the stomach and intestines are indicated by inappetence, sometimes flatulence, passage of flatus, constipation with small, round, mucous-coated balls passed in small numbers, and by slight transient colics, pawing, looking at the flanks, and retraction of the abdomen. The retention of bile and destruction of blood elements are indicated in a deeper yellow of the conjunctiva and visible mucosæ, and in a yellow, brown or red color of the urine. There may be tenderness of the abdomen, but this, like the colics, is moderate, the senses being blunted by the attendant stupor which is usually even greater than in the thoracic forms. Urination may become frequent with straining, and the urine may become turbid, opaque, with flocculi of cystic epithelium and mucus, and even albumen. In from three to five days diarrhœa supervenes, the fæces becoming soft, pulpy, watery, glairy or bloody, and escaping through a permanently dilated sphincter. The diarrhœa may alternate with periods of torpor or complete inactivity, otherwise tenesmus of the rectum is marked. The exposed rectal mucosa is congested, of a deep red or it may be of a dark violet hue. Eversion is not unknown.
In the worst cases death may ensue by the third or fourth day, but in others the diarrhœa is critical and heralds an improvement which goes on to a speedy recovery. In still other cases the bowel troubles continue, the fever does not give way and the privation of food and rapid metamorphosis of tissue produce steady emaciation and fatal marasmus.
A striking feature of the gastro-intestinal disease is the extraordinary susceptibility to laxatives. So much is this the case that I have known of two drachms of aloes proving fatal by superpurgation in a large, mature Percheron horse. It is never safe to use laxatives in equine influenza until one has ascertained whether in the special form of the epizoötic in question the gastro-intestinal organs are or are not especially involved.
Disorders of the eye are so common or constant as to have procured for certain epizoötics the name of pink eye. They set in suddenly, and equally in both eyes, with infiltration of the lids and particularly of the mucosa which is of a more or less deep red, and may bulge between the margins of the eyelids, (chemosis). The flow of tears is profuse, seropurulent matter accumulates at the canthi and in the lachrymal sacs, vision is impaired and there is intolerance of light. The cornea becomes bluish, cloudy or milky white, with a red zone around its margin and, above all, on the adjacent sclerotic. In some cases the aqueous humor becomes turbid or flocculent, and the iris changes its clear, healthy dark lustre for a dull brown or yellow tint. The tension of the globe may be materially encreased. They are readily distinguished from recurrent ophthalmia by the attendant weakness, stupor and hyperthermia, and by their non-recurrence in case the patient survives.
The nervous symptoms are especially manifest in the sudden seizure, great prostration, extreme weakness, profound stupor or lassitude, the staggering gait, in bad cases, insensibility to voice, slap or, it may be, even to the whip, the rigidity of the loins, their insensibility to pinching, the difficulty of turning in a short circle, or of backing. The high fever, disproportionate to the appreciable local lesions, and its sudden improvement at the critical period, the excessive weariness and the disposition to lie down contrary to the habit of other inflammatory chest diseases are further indications.
This may go on to coma, there may be more or less complete anorexia, muscular trembling, paresis, especially of the hind limbs, or delirious manifestations indicating meningitis.
Rheumatoid attacks of the muscles and joints usually appear in the advanced stages of the disease, but may appear earlier. They may occur in any latitude but seem to be especially common in cold, damp, inclement northern regions, and at seasons when climatic vicissitudes are sudden and extreme. These may appear suddenly and disappear with equal rapidity, or they may last for a time during and even after an apparent recovery in other respects. When the joints are involved they usually become engorged with exudates in the synovial membranes.
Lameness in either fore or hind limb may assume an intermittent type developed by exercise and subsiding with rest, evidently bespeaking local arterial embolism, and in such cases it is likely to persist for months.
A tendency to transudations and dropsical effusions is common in severe cases, showing especially in the filling of the legs, but in certain epizoötics, these become strikingly prevalent and have secured for such a special name (epizoötic cellulitis). Apart from the limbs these affect particularly the inferior surface of the chest and abdomen. The swellings are not necessarily hot nor painful nor petechiated as in petechial fever, yet they may merge into that affection or they may become phlegmonous and develop abscess.
Complications of many kinds are to be looked for, pregnant mares may abort; laminitis may set in; the microbes of strangles, contagious pneumonia, cerebro-spinal meningitis, septicæmia, pyæmia, etc., may take occasion to attack the debilitated system, and thus complex diseases and manifestations are developed.
Morbid Anatomy. The lesions may predominate in different organs in different subjects and successive epizoötics. It is a protean disease and may expend its main energy on any one of a number of different organs or systems of organs.
In the slighter cases the lesions are often largely confined to the anterior part of the respiratory organs. The fauces, pharynx, larynx, guttural pouches and nasal mucosa are tumified, congested, red and covered with mucous, and this condition may extend down to the bronchia. In such cases the blood is normal or may coagulate with undue readiness and firmness. The pharyngeal and intermaxillary lymph glands are red and congested in their outer zone.
In the more severe cases the alterations in the blood are perhaps the most constant of the morbid features. The blood is fluid and incoagulable, or the clot is soft, diffluent and black, the red globules are crenated or broken up, and show little tendency to adhere in rouleaux. The escaped hæmatoidin accumulates in masses in the serum in crystalline forms, giving it a high staining power when a line is drawn with it on white paper. Fatty globules also float in the mass. The leucocytes are relatively very much encreased and the red globules diminished. Dieckerhoff found 30,000 and Trasbot 40,000 leucocytes in a cubic millimetre.
The diffluence is not constant. Blood drawn in the earlier stages of the disease, coagulates with extraordinary firmness, influenced, doubtless, by the encrease of the leucocytes, the disintegration of the blood globules, and the liberation of globulins. This serves also to partially explain the early and sudden deaths from coagula in the heart and large vessels, which are occasionally met with. Such clots in the heart are often found adherent to the valvular or ventricular endocardium which at such points shows cloudy swelling, thickening, cell proliferation and even encreased vascularity and granular elevations.
In advanced cases, however, the prominent features are usually acidity, blackness, and incoagulability of the blood, its resistance to oxygen, altered and broken down red globules, free coloring matter, relative encrease of white cells, and, if necropsy has been delayed, the abundance of septic microbes (cocci and bacilli). Petechiæ are abundant on the serosæ especially on the pericardium.
Lesions of the alimentary mucosa are very constant. There may be stomatitis, with tumid follicles and even ulcers (Kowalavsky). In the stomach the right sac has its mucosa thickened, softened, red, congested, petechiated and discolored. The summits of the folds may be ulcerated (Labat). Similar lesions are presented in the small intestines. The agminated glands may show many rounded elevations, with or without open discharging follicles. The mucosa is covered with a muco-purulent material. Otherwise, the small intestines, like the stomach, are usually empty. The large intestines present similar lesions, the nodular elevations often representing the solitary glands, and the masses of ingesta are likely to be dry and indurated, in the earlier stages or semiliquid in old standing cases. The peritoneum may be congested, petechiated and at points infiltrated and usually contains a reddish serum in variable quantity. The mesenteric glands are more or less enlarged and congested.
The liver shows more or less congestion as in other infectious diseases localized in the bowels. It usually has a parboiled appearance, and yellowish gray areas of necrosis may be manifest, or again, fatty degeneration may be present. Petechiæ, and even small blood clots may be found on or beneath the capsule. The pancreas, and, still more, the spleen may be the seat of congestion or engorgement but this is far from constant.
The capsule of the kidney may be petechiated or elevated at points by serous exudate or extravasation. The surface of the organ and of sections show a mottling with darker and lighter areas, and petechiæ and patches of congestion may be found on the bladder and urethra.
The nervous centres exceptionally show meningeal congestions, and exudations, and petechiæ as has been noted of other serosæ.
Lesions of the eye may be confined to the mucosa, or they may extend to the membrane of the aqueous humor, the iris, or even the deeper structures.
Other lesions such as laminitis, bursitis, arthritis, like those attendant on abortion need no special description.
When pulmonary lesions are extensive, the bronchial mucosa is not only softened, opaque and covered with a serous, or muco-purulent discharge, but deeply congested and petechiated. When the chest is opened there is usually an effusion, pale straw, red or bloody and more abundant than in contagious pneumonia. False membranes may exist and show a blackish tint from extravasated blood. The lung fails to collapse and shows on the surface and throughout its substance petechiæ and small black infarctions. In some instances the whole lung is blood gorged, black, almost jelly like, as in acute congestion. In others these are limited infiltrations, concentrated especially in the anterior and lower parts, and almost invariably affecting both right and left lungs. The infiltration is circumscribed in area in comparison with the attendant fever and constitutional disturbance, resembling in this respect, the lesions of contagious pneumonia. It differs however in having a greater tendency to liquid infiltration of the connective tissue, and but for the lack of such tissues in the horse’s lung it would tend to approximate to the lesions of lung plague in cattle. It shows a distinct thickening of the interlobular septa, a tendency to extension to the pleura, and to issue in pleural and subpleural infiltration, and to a more copious effusion into the pleural cavity than in either fibrinous or contagious pneumonia. The lung tissue may be granular and hepatized, but far more frequently it is only splenized, the lung being the seat of a bloody infiltration, yet retaining much of its elasticity and coherence. Portions may be infarcted and black and large areas may have a pale or parboiled appearance, and gangrene is by no means uncommon.
Diagnosis. This is based largely on the suddenness of the attack, its epizoötic character, the numbers attacked in rapid succession, and over a large area as contrasted with contagious pneumonia, the sudden and extreme prostration and weakness, the swelling, watering and discoloration of the eyes, the mildness of the average case, the congestion of the upper air passages, and in the mild cases a comparative immunity of the lungs, the irritability or congestion of the gastro-intestinal mucosa, and the history of the case:—the arrival of the infected horses within a few days from an infected place, or coming through infected channels, or the attack of new arrivals in a previously infected stable, or the known advance of the disease towards the place where the patients are, will usually serve to mark the true nature of the affection.
As a help to correct diagnosis we give below some of the prominent conditions and phenomena of the three forms of lung disease known as fibrinous pneumonia, contagious pneumonia, and the pneumonia of equine influenza:
| Pneumonia: | Pneumonia: | Pneumonia: |
|---|---|---|
| Croupous Fibrinous. | Contagious, of Equine Animals. | of Equine Influenza. |
| From climatic vicissitude, exposure, etc. Attacks exposed animals only, and all at once | Slow succession of cases in the same stable, irrespective of climate or exposure | Rapid succession of cases in the same stable or locality, irrespective of climate or exposure |
| Prevails in inclement seasons, spring, autumn, (Winter) | Any season: worse in inclement season | Any season: worse in inclement season |
| Infection from close proximity, contact, stall, manger, rack, bucket, trough, etc.: Spread slow | Infection spreads widely and rapidly through the air. Spread rapid and often general | |
| Carried in manure, on harness, wagons, clothes, etc. | Carried in manure, on harness, wagons, clothes, etc. | |
| Incubation, 3–10 days | Incubation, 1–2 days | |
| Rigor may be late: after exudation has commenced | Rigor early and well marked, before exudation | Rigor not always well marked |
| Sets in slowly or with acute congestion; appetite and pulse vary with inflammation | Sets in slowly, cough, dulness, impaired appetite, pulse rapid, prostration slight | Profound nervous prostration like opium poisoning, appearing early and suddenly |
| Nasal discharge, watery or rusty, later muco-purulent | Nasal discharge, yellow | Nasal discharge, watery, may become yellow |
| Eye pink, dark red | Eye yellow, rarely swollen or watery | Eyelids bloodshot (pink eye), violet, madder hue, swollen, watery, closed |
| Temperature rises with inflammation | Temperature rises early and extremely, before exudation, 104°–107° | Temperature rises early and extremely, in some hours, 104°–107° |
| Swelling of limbs rare | Limbs swell rarely | Limbs often swell greatly |
| Rheumatoid arthritis may follow | Rheumatoid arthritis may set in; often in advanced stage | |
| Crepitation more constant around the exudation | Crepitation less constant around the exudation | Crepitation may escape recognition |
| Exudation (Hepatization) in lung, lower, posterior, anterior, or central, usually undivided area | Exudate affects lower or anterior border of lung; often in small isolated areas or around bronchia; less blood engorgement than in fibrinous pneumonia | Exudate less granular than in pneumonia; forms in or gravitates to lower part of lung. Congestion passive |
| If pleurisy effusion may be copious | Pleural effusion infrequent, or limited, though pleurisy is common | Pleural effusion frequent and abundant |
| Abscess not infrequent | Abscess rare | Abscess not infrequent |
| Pulmonary gangrene infrequent | Pulmonary gangrene and sequestra frequent | Infarctions, sequestra, and cavities not uncommon |
| Pericarditis infrequent | Pericarditis frequent | Pericarditis frequent |
| Blood, decrease of red globules; encrease of white, hæmatoblasts, fibrine formers and soda salts | Less altered than in either of the other forms. Shows cocco-bacilli in the earlier stages: streptococci later | Blood at first clots firmly, later becomes, thick, black, sizy, hæmatosis tardy. Reaction acid. |
| Coagulation firm, buffy coat | Coagulum loose, buffy coat slight | |
| Hepatic congestion, not hepatitis | Hepatic congestion excessive, hepatitis, necrotic changes | Hepatic congestion excessive, hæmorrhagic; fatty degeneration |
Prognosis. Mortality. As usually met with and under favorable conditions, equine influenza is a mild disease. In 1872 when the disease, sweeping the continent and hardly sparing an equine animal, might be assumed to have reached its maximum, the actual deaths varied from 2 per cent. in country districts to 7 per cent. in large cities. The same holds for Europe where Friedberger and Fröhner gives 4 to 5 per cent. Früs (Denmark) 1 per cent., Aureggio (Italy) 3 per cent., Siedamgrotzky 10 per cent. Much depends on conditions: In horses infected in transit on a long railroad journey it may be 100 per cent. and in fat dealer’s horses, out of condition for active work it usually reaches a high figure. If the patients are kept at work the complications and mortality run very high. The same applies to debilitated animals kept in close, foul, ill-aired stables, or reduced by exhausting or long standing diseases. The very young and the senile suffer more than animals in middle life and vigorous condition. Finally the parts invaded have a controlling effect. The milder cases affecting the upper air passages only, nearly all recover, in those showing abdominal lesions the indications are still favorable; while with double pulmonary and pleural lesions the patient is too often in a hopeless condition. Brain lesions are almost equally redoubtable.
The actual money losses, in an epizoötic of influenza, are more in the way of the loss of work and the complete stagnation of trade in all departments, than in the number of deaths. Yet even in this sense it may prove more ruinous than would a disease having a less universal sway, though far more fatal to the animals attacked.
Treatment. A disease like this, which tends to spontaneous and perfect recovery, needs mainly dietetic and hygienic care in the vast majority of cases. Rest is a prime consideration in a pure genial atmosphere. In the summer season, in the absence of rainstorms, an open air life, at pasture is the best. Shelter must be had in case of storms, and in the cold season a clean, sweet, roomy well-aired loose box, with a sunny exposure, is important. Clothing, bandages, blankets and even hoods may be required if there is any tendency to chill. Food should be laxative, cooling and of easy digestion. Bran mashes, scalded oats or barley, ensilage, roots, potatoes, apples, fresh grass or scalded hay may be suggested. Milk has been strongly advocated, from twelve to fifteen quarts a day, and linseed tea as being especially adapted to the irritable stomach and bowels. Food should be given often, in small quantities so as not to destroy the appetite.
Costiveness is best met by injections of water, blood warm, or if there is much hyperthermia, of cold water. This latter stimulates the peristalsis more actively and at the same time lowers the temperature. By unloading the large intestines it removes irritants, without danger of encrease of congestion or diarrhœa.
If anything more is wanted for these mild cases, small doses of stimulating diuretics or diaphoretics may be given. Sweet spirits of nitre ½ oz. or liquor of acetate of ammonia 2 oz. may be given twice a day, the latter in the drinking water or gruel. In the absence of these saltpeter ½ oz, or potassium acetate ½ oz. may be given.
In the more severe cases more active treatment is resorted to, but in all cases one should avoid measures that tend to greatly depress the vital powers and especially the circulation. Heroic treatment has been all but universally condemned and yet Trasbot claims to have had excellent results from a moderate venesection (2–5 qts.) in strong, muscular, well conditioned animals. The blood became more fibrinous, the general symptoms improved and complications were far less marked. During twenty years, in a large number of cases, it had constantly the same results, restoring appetite, opening the closed eye, imparting new life, lowering temperature, and checking congestions. The results were best in all cases when it was employed early, but they were almost equally good when later congestions set in, or when the ordinary inflammatory localizations were advancing, and he found the measure hurtful only when, in the advanced stages, the animal was worn out, and destitute of all power of recuperation.
Antipyretics have been lauded and decried, and it is doubtless best to use them with due discrimination and caution. Acetanilid, the agent in most common use, is a powerful cardiac depressant, and in this disease the heart is often already dangerously weak. Yet in cases with very high temperature, seriously threatening life, acetanilid in doses of 2 drams, repeated every second or third hour until the temperature falls, and thereafter twice or thrice daily, for a day or two, may save the patient. Similarly, where there are indications of violent headache (drooping head, eyelids and ears, congested and watery conjunctiva, stupor or irresponsiveness) a dose or two of acetanilid with the same amount of sodium bromide will often give material relief. The general suffering and disorder attendant on the cephalalgia, if allowed to continue, prove a direct bar to improvement, and endanger complications that might otherwise be escaped. On the other hand, there is constant danger from too large doses, or a too long continued use of acetanilid in influenza. Phenacetin may be substituted in 2 dram doses, the action being somewhat more prompt and transient. As less dangerous than the coal tar antipyretics, we may fall back on such agents as sodium salicylate, ½ to 1 oz., or sulphate of quinia, 20 grs.
Elimination of toxins and waste products is to be secured and this is more safely conducted by the kidneys or skin than by the irritable alimentary canal. Plenty of pure cold water is one of the best and simplest resorts. Aside from this, where there is much hyperthermia, bicarbonate of potash or soda will serve the various purposes of an antidote to the acid blood, an eliminant and an antithermic. Under the same circumstances saltpeter may be resorted to in ½ oz. doses twice daily. When, however, the heart is weak it is better to employ ammoniacal or etherial diuretics:—spirits of nitrous ether, 1 oz. or liquor of acetate of ammonia, 2 to 4 ozs. By combining these with extract of belladonna and camphor a fairly standard prescription may be prepared.
Inhalations of warm water vapor, rising from hot water or a hot mash in a bucket, over one end of which a bottomless bag is drawn, while the other end receives the nose of the horse, will greatly relieve the irritation and the cough. It can be made even more soothing by introducing a little alcohol, eucalyptol, menthol, camphor, poppy-heads, or other anodyne. Or the water vapor may be set free in a close stall from a boiling tea-kettle or a steam pipe, and an admixture of sulphurous acid made by burning a few pinches of sulphur, more or less according to the size and closeness of the stall. If the stall is tight enough a steam bath may be given with much profit in the early stages.
Counter irritants applied to the throat, or, if need be, to the breast and sides of the chest will often give material relief, acting as derivatives and probably also by modifying the globulins in the exudate and thus influencing the course of the disease. In case of sore throat of a very high type it may be best to apply a compress or poultice, or even a piece of sheepskin for a day or two, until, by antithermics, cooling diuretics and soothing inhalations, the severity of the inflammation has abated. The common mustard pulp made with tepid water, rubbed in, and covered by paper, may be applied for an hour; or the soap liniment (soap 6 ozs., camphor 3 ozs., and proof spirit, liquor ammonia and linseed oil aa 1 pint) may be rubbed on repeatedly; or a blister of cantharides may be used.
The ophthalmia may be treated by a moist atmosphere, a few drops twice daily of a solution of atropine beneath the lids, a similar treatment with pyoktanin, (1:1000), or a solution of mercuric chloride (1:2000).
In case of gastro-intestinal inflammation elimination is to be sought by ⅓d the usual laxative dose, supplemented if need be, by injections. Half a pint of olive oil with 20 grs. calomel will usually be well borne. Counter irritants may be applied to the abdomen, and the bowels must be carefully watched and any inactivity or derangement corrected. A slight diarrhœa is not to be too hastily checked as it may serve at once to eliminate offensive matters and subdue mucous inflammation. Solutions of flax seed, gum, or slippery elm in the drinking water may serve a good end.
In case of cardiac weakness with intermittent or irregular pulse, hurried breathing, and an undue contrast between the violence of the heart action and the weakness of the pulse, circulatory stimulants are called for. Digitalis 10 grains twice daily, strophanthus tincture 1½ dr., strophanthin subcutem ¼ grain, caffeine 5 grains, veratrine ⅒th grain, or strychnia 2 grains.
Nervous symptoms will exceptionally demand the application of cold water or even ice or snow to the head, with counterirritants to the sides of the neck or chest, and the internal use of bromides, iodides, chloral or other nerve sedative.
Other complications must be treated according to their indications.
As the skin becomes cooler and more moist, and the pulse slower and fuller, a tonic and stimulating treatment may be desirable. Gentian 4 drs., saltpeter 4 drs., sal-ammoniac 2 drs. may be given night and morning, or in case of great debility ammonia carbonate may replace the sal-ammoniac. Or the gentian may be replaced by nux vomica, and the ammoniacal preparations by alcoholic ones.
When prostration becomes extreme and stimulants and bitters appear inadequate, transfusion of blood from a healthy horse may save the patient’s life, or a normal salt solution sterilized may be introduced into the vein.
The first method is accomplished through a caouchouc tube with a short tube of silver inserted in each end; the jugular groove of each horse is washed and disinfected, and the vein opened; the tube disinfected with a salicylic acid solution, and cleared out with boiled water is inserted upward into the vein of the sound horse, and when the blood begins to flow the other end is inserted downward into the vein of the sick one. In this way the blood is allowed to flow from the one to the other, the finger being kept on the pulse of the patient to detect any faltering, which like heaving up of the head or rolling of the eyes, may be taken to indicate undue arterial tension, or disturbed brain circulation, and should be the signal for an arrest of the flow. To effect this, pinch the tube in the centre, and wait a minute or so; if the symptoms subside the current may be reopened and a little more carefully admitted, but if not the tube may be withdrawn and the wounds pinned up.
The normal salt solution, .6 per cent., is sterilized by boiling, and placed in a sterilized vessel where it is allowed to cool to the body temperature; then a caouchouc tube furnished with a silver tube at one end and sterilized as for transfusion of blood, is filled with the solution and the vessel containing the latter having been placed at a level higher than the patient, the tube is used as a syphon. When the liquid flows in full stream the silver tube is inserted downward into the jugular of the patient and the liquid is allowed to flow in, subject to the same precautions as regards sudden blood tension as in the case of the transfusion of blood.
Prevention. No country appears to have attempted the absolute exclusion of the disease or the extinction of the germ by a compulsory quarantine and disinfection. The nearest approach to this is in Prussia where in the event of an outbreak of equine influenza, the official veterinarians and police authorities must send in reports to be published in the official papers and communicated to the directors of government breeding studs and to the army authorities. We have here the germ of an effective system of extinction, for if those in charge of government horses in an infected country can protect them against infection, much more could such protection be secured by putting an end to the infection which is now allowed to remain generalized. Moreover in our great outbreak of 1872–3, when germ-potency and all but universal susceptibility were so remarkable, effective quarantine showed the most signal successes, in the resulting immunity of Vancouver’s Island, Prince Edward Island, the whole of the West Indies except Cuba, Central and South America, and isolated districts in Mexico.
Sanitary police in this disease has been abandoned mainly because the virus is so diffusive on the air that quarantine must be more than usually comprehensive to prevent extension of infection, and because the disease is fatal only in a small percentage of cases, so that the loss is apparently minimized. But a panzoötic like that of 1872–3, prostrating 1,000,000 horses, asses and mules in the United States for one to two weeks, and paralyzing the agriculture and commerce of the continent for that length of time, may well make one hesitate to supinely accept for all time an evil, which, experience has shown, can be circumscribed and stamped out. When horse owners, legislatures and veterinarians can be educated up to the needs of the case our yearly local losses from equine influenza, and the occasional all pervading epizoötics of this disease can probably be abolished by the extinction of the germ on the Continent. To achieve this result an immediate large outlay would be well spent. In a new generation, or a new century perhaps, this desirable object may be achieved.
Meanwhile the individual owner can do something to secure a partial protection. On farms and in barracks the animals may be secluded from all other equine animals during the local prevalence of the disease. Men, dogs, and wild animals can be similarly excluded. Litter, fodder, bags, clothing, manure, vehicles, etc., from infected stables and places must be carefully guarded against. Newly purchased animals, carried in any public conveyance, or kept or fed in any public yard or stable must be quarantined at a considerable distance from others, and treated by disinfectant sponging and fumigation before they are allowed to mingle with other equine animals. Stables where the disease has occurred must be thoroughly disinfected, together with all manure made during the epizoötic and for some time thereafter.