Special Report on Diseases of Cattle Part 58

These experiments and observations indicate that the types of tubercle bacilli are very inconstant, and that under suitable conditions they readily change both in morphology and in virulence. A similar conclusion was reached by other investigators in working with the avian and porcine types of tubercle bacilli several years ago, and was reasonably to have been expected with the human and bovine types.

Later investigations made by Park and Krumweide, of the Research Laboratory of New York City, Novick, Richard M. Smith, Ravenel, Rosenau, Chung Yik w.a.n.g, and others tend to show the incidence of bovine infection in the human family. Chung Yik w.a.n.g stated in 1917 that studies of 281 cases of various clinical forms of tuberculosis in Edinburgh, Scotland, resulted in the isolation of the bovine tubercle bacilli in 78.4 per cent of cases under the age of 5 years, in 70.3 per cent between the ages of 5 and 16, and in 7.8 per cent over the age of 16. This investigator states that from the prophylactic point of view any measure resorted to in combating the disease should be directed not only against the human spread of infection, but also, more particularly in children's cases, against the bovine source of infection.

Ravenel, in summarizing the work of Drs. Park and Krumweide, as well as others throughout the world, gives the following results:

Of 63 children dying of tuberculosis at the babies' hospital 59 cases proved to be human infection and 4 bovine, a percentage of 6-1/3.

Of 9 children dying of tuberculosis at the foundling hospital 4 proved to have derived their infection from human sources and 5 from bovine, a percentage of 55.

Of a total of 88 children under 5 years of age who died of tuberculosis 77 proved to have derived their infection from human sources and 11 from bovine, a percentage of 12-1/2.

Combining the cases studied in New York with those of other observers in different parts of this country and Europe, the following results are obtained:

Adults, 787 cases--777 human and 10 bovine infection.

Children, 5 to 16 years, 153 cases--117 human and 36 bovine infection.

Children under 5 years, 280 cases--215 human and 65 bovine infection.

The figures of the foundling hospital show the real danger of unprotected cows' milk.

The conclusion from these studies is inevitable, namely, that in children, in addition to the large number of deaths which occur from bovine infection, there are many cases of infection resulting in deformities, necessitating operations more or less severe in character and which frequently leave the patient disfigured permanently.

It must be plain to all, from these recent developments, that too much has been made of the slight differences in cultural characteristics, in morphology, and in virulence which have been observed in some cases in comparing the human and the bovine bacilli. The observations were interesting, and it was important that they be followed up until their significance was made entirely clear, but it was an almost unpardonable error, from a sanitary point of view, to promulgate sweeping generalizations calculated to arrest and abolish important measures for preventing human tuberculosis before the soundness of these generalizations had been established by a thorough course of experimentation.

When Koch said in the British Congress on Tuberculosis that he should estimate the extent of infection by the milk and flesh of tuberculous cattle and the b.u.t.ter made of their milk as hardly greater than that of hereditary transmission, and that he therefore did not deem it advisable to take any measures against it, he went far beyond what was justified by any experiments or observations which he reported, and he did a great deal of harm, which will be manifested for years to come, to those who endeavor to guard the human race from the dangers of animal tuberculosis. The researches which have been alluded to make these dangers more definite and certain than they have appeared before, and sanitarians should therefore most earnestly endeavor to counteract the erroneous and harmful impression which was made by Koch's address at London and his subsequent address at the International Conference on Tuberculosis at Berlin.

VACCINIA OR COWPOX.

Variola of cattle, more correctly vaccinia, is a contagious disease of cattle which manifests its presence through an elevation of temperature, a shrinkage in milk production, and by the appearance of characteristic, pustular eruptions, especially upon the teats and udders of dairy cows.

Although this is a contagious disease, strictly speaking, it is so universally harmless and benign in its course that it is robbed of the terrors which usually accompany all spreading diseases, and is allowed to enter a herd of cattle, run its course, and disappear without exciting any particular notice.

The contagion of cowpox does not travel through the air from animal to animal, but is transfused only by actual contact of the contagious principle with the skin of some susceptible animal. It may be carried in this manner, not alone from cattle to cattle, but horses, sheep, goats, and man may readily contract the disease whenever suitable conditions attend their inoculation.

An identical disease frequently appears upon horses, attacking their heels, and thence extending upward along the leg, producing, as it progresses, inflammation and swelling of the skin, followed later by pustules, which soon rupture, discharging a sticky, disagreeable secretion. Other parts of the body are frequently affected in like manner, especially in the region of the head, where the eruptions may appear upon lips and nostrils, or upon the mucous surfaces of the nasal cavities, mouth, or eyes.

Variola of the horse is readily transmitted to cattle, if both are cared for by the same attendant, and, conversely, variola of cattle may be carried from the cow to the horse on the hands of a person who has been milking a cow affected with the disease.

The method of vaccination with material derived from the eruptions of cowpox as a safeguard against the ravages of smallpox in members of the human family is well known. The immunity which such vaccination confers upon the human subject has led many writers to a.s.sert that cowpox is simply a modified form of smallpox, whose harmless attack upon the human system is owing to a certain attenuation derived during its pa.s.sages through the system of the cow or horse. The results of numerous experiments which have been carried out for the purpose of determining the relationship existing between variola of the human and bovine families seem to show, however, that although possessing many similar characteristics, they are nevertheless distinct, and that in spite of repeated inoculations from cattle to man, and vice versa, no transformation in the real character of the disease ever takes place.

_Symptoms._--The disease appears in four to seven days after natural infection, or may evince itself in two or three days as the result of artificial inoculation. Young milch cows are most susceptible to an attack, but older cows, bulls, or young cattle are by no means immune. The attack causes a slight rise in temperature, which is soon followed by the appearance of reddened, inflamed areas, princ.i.p.ally upon the teats and udder, and at times on the abdominal skin or the skin of the inner surface of the thighs. In a few cases the skin of the throat and jaws has been found similarly involved. If the affected parts are examined on the second day after the establishment of the inflammation numerous pale-red nodules will be found, which gradually expand until, within a few days, they reach a diameter of one-half inch or even larger. At this period the tops of the nodules become transformed into vesicles which are depressed in the center and contain a pale, serous fluid. They usually reach their maturity by the tenth day of the course of the disease and are then the size of a bean.

From this time the contents of the vesicles become purulent, which requires about three days, when the typical pox pustule is present, consisting of a swelling with broad, reddened base, within which is an elevated, conical abscess varying from the size of a pea to that of a hazelnut.

The course of the disease after the full maturity of the pustule is rapid if outside interference has not caused a premature rupture of the small abscess at the apex of the swelling. The pustules gradually become darker colored and drier until nothing remains but a thick scab, which at last falls off, leaving only a slight, whitish scar behind. The total duration of the disease covers some 20 days in each animal, and owing to the slow spread of the infection from animal to animal, many weeks may elapse before a stable can be fully freed from it. The fallen scabs and crusts may retain their contagious properties for several days when mixed with litter and bedding upon the floor of the stable, and at any time during this period they are capable of producing new outbreaks should fresh cattle be brought into the stalls and thus come into actual contact with them. Again, the pustules may appear, one after another, on a single animal, in which case the duration of the disease is materially lengthened.

_Treatment._--In herds of cattle that regularly receive careful handling, no special treatment will be found necessary beyond the application of softening and disinfecting agents to such vesicles upon the teats as may have become ruptured by the hands of the milker. Carbolized vaseline or iodoform ointment will be found well suited to this work. In more persistent cases it may be found desirable to use a milking tube in order to prevent the repeated opening of the pustules during the operation of milking. Washing the sores twice daily with a weak solution of zinc chlorid (2-1/2 per cent solution) has been found to a.s.sist in checking the inflammation and to cleanse and heal the parts by its germicidal action.

When the udder is hard, swollen, and painful, support it by a bandage and foment frequently with hot water. If calves are allowed to suckle the cows the pustules become confluent, and the ulcerations may extend up into the teat, causing garget and ruining the whole quarter of the udder.

As young cows are most susceptible to variola, the milker must exercise constant patience with these affected animals so long as their teats or udders are sore and tender, else the patient may contract vicious habits while resisting painful handling. The flow of milk is usually lessened as soon as the fever becomes established, but is again normal with the return of perfect health.

The practice of thorough cleanliness in handling or milking affected cattle may, in many instances, prevent the dissemination of the trouble among the healthy portion of the herd, but even the greatest care may prove insufficient to check the spread until it has attacked each animal of the herd in turn.

ACTINOMYCOSIS (LUMPY JAW)

[Pls. x.x.xIX-XLI.]

Actinomycosis, also known as lumpy jaw, big jaw, wooden tongue, etc., is a chronic infectious disease characterized by the formation of peculiar tumors in various regions of the body, more particularly the head, and is due to the specific action of a certain fungus-like germ (actinomyces).

This fungus is an organism which occurs in the tissues in the form of rosettes, and it has therefore been termed the "ray fungus." The disease is not directly transmitted from one animal to another, but it seems apparent that the fungus is conveyed into the tissues by various feedstuffs through slight wounds of the mucous membrane of the mouth, decayed teeth, or during the shedding of milk teeth. The ray fungus is found in nature vegetated on gra.s.ses, on the awns of barley, the spears of oats, and on other grains.

Quant.i.ties of the fungi have been found between the vegetable fibers of barley which had penetrated the gums of cattle and on the awns of grain embedded in the tongues of cows.

Although actinomycotic tumors on cattle had been the object of study for many years, it was not until 1877 that the constant presence of actinomyces was pointed out by Bollinger, of Munich, and since that time considered the cause. This fungus was observed in these tumors as early as 1860 by Rivolta, and by others subsequently, without having been suspected as causing them.

Since Bollinger's publication much work has been done, many observations made, and many hitherto obscure disease processes brought into relation with this fungus. Furthermore, a similar disease in man was first definitely shown to be a.s.sociated with the same fungus in 1878 by Israel, and in the following year Ponfick pointed out that the disease described by Bollinger in animals and that found by Israel in man were due to the same cause; that is, that the fungi described by these observers were one and the same.

The tumors and abscesses wherever they may be are all found to be the same in origin by the presence of the actinomyces fungus. When they are incised, a very close scrutiny with the naked eye, or, at most, a hand lens, will reveal the presence of minute grains which vary from a pale-yellow to a sulphur-yellow color. They may be very abundant or so few as to be overlooked. They are embedded in the soft tissue composing the tumor or in the pus of the abscess. With a needle they are easily lifted out from the tissue, and then they appear as roundish ma.s.ses about one-half millimeter (1/50 inch) in diameter. To anyone familiar with the use of a microscope the recognition of these grains or particles without any previous preparation is a comparatively easy task.

When examined in the fresh condition under a microscope magnifying up to 250 diameters the general structure is made out without much difficulty.

These grains consist of collections of minute, roundish ma.s.ses. Their outer surface is made up of club-shaped bodies all radiating from the center of the ma.s.s (see Pl. x.x.xIX, fig. 2), somewhat like a rosette. If the fungus is crushed, the interior is found made up of bundles of very fine filaments, which are probably continuous into the club-shaped bodies. The addition of a dilute solution of caustic soda or potash greatly aids the examination, as it removes the layer of cells adhering to the fungus, which obscures the structure. Now and then these grains are found to be in a calcified condition. The exterior is incrusted in lime salts, which are dissolved by adding some weak dilute acid, like acetic acid. Only by this procedure can the fungus be definitely recognized when in a mummified condition.

These are the bodies whose presence causes sufficient irritation in the tissues into which they find their way to set up inflammatory growths.

These growths increase as the fungus continues to multiply until they reach enormous dimensions, if the affected animal is permitted to live long enough. The true nature of this parasite is not yet definitely settled, although many excellent observers have occupied themselves with it.

According to earlier observers, it is a true fungus. Later ones are inclined to place it among the higher bacteria. Present knowledge concerning the actinomyces growth indicates that it should be cla.s.sified with the higher bacteria or trichomycetes.

Whatever the situation of the disease caused by actinomyces may be, its nature is fundamentally the same and peculiar to the fungus. The pathological details which make this statement clear can not be entered upon in this place, nor would they be of any practical value to the farmer.

We will simply dwell upon a few obvious characters.

The consistency of the tumor varies in different situations according to the quant.i.ty of fibrous or connective tissue present. When very little of this is present the tumor is of a very soft consistency. As the quant.i.ty of connective tissue is increased the tumor is firmer and of a more honeycombed appearance. The individual actinomyces colonies are lodged in the s.p.a.ces or interstices formed by the meshwork of the connective tissue.

There they are surrounded by a mantle of cellular elements which fill up the s.p.a.ces. By sc.r.a.ping the cut surface of such a tumor these cell ma.s.ses inclosing the fungi come away, and the latter may be seen as pale-yellow or sulphur-yellow specks, as described above.

_Location of the disease._--In cattle the disease process may be located both externally, where it is readily detected, and in internal organs. Its preferred seat is on the bones of the lower and upper jaws, in the parotid salivary gland in the angle of the jaw, and in the region of the throat. It may also appear under the skin in different parts of the body. Internally it may attack the tongue and appear in the form of a tumor in the mouth, pharynx, or larynx. It may cause extensive disease of the lungs, more rarely of the digestive tract.

It appears, furthermore, that in certain districts or countries the disease seems by preference to attack certain parts. Thus in England actinomycosis of the tongue is most prevalent. In Denmark the soft parts of the head are most p.r.o.ne to disease, while in Russia the lips are the usual seat. In certain parts of Germany actinomycotic tumors are most frequently encountered in the throat region and in the jawbones.

A description of actinomycosis of the jaw (lumpy jaw) and of the tongue has already been given in a previous chapter, and hence they will be dealt with here only very briefly. When the disease attacks the soft parts of the head a rather firm swelling appears, in which are formed one or more smaller projecting tumors, varying from the size of a nut to that of an egg. These push their way outward and finally break through the skin as small, reddish, funguslike bodies covered with thin sloughs. Or the original swelling, in place of enlarging in the manner described, may become transformed into an abscess which finally bursts to discharge creamy pus.

The abscess cavity, however, does not disappear, but is soon filled with fungus-like growths, which force their way outward through the opening.

When the tumors are situated within the cavity of the pharynx they have broken through from some gland, perhaps beneath the mucous membrane, where the disease first appeared, and hang or project into the cavity of the pharynx, either as pendulous ma.s.ses with slender stems or as tumors with broad bases. Their position may be such as to interfere with swallowing and with breathing. In either case serious symptoms will soon appear.

The invasion of the bones of the jaws by actinomycosis must be regarded as one of the most serious forms of the disease. (Pls. x.x.xIX, XL.) It may start in the marrow of the bone and by a slow extension gradually undermine the entire thickness of the bone itself. The growth may continue outward, and after working its way through muscle and skin finally break through and appear externally as stinking fungoid growths. The growth may at the same time work its way inward and appear in the mouth. The disease may also begin in the periosteum, or covering of the bone, and destroy the bone from without inward.

Actinomycosis of the lungs is occasionally observed, and it is not improbable that at times it has been mistaken for tuberculosis. The actinomyces grains are, however, easily observed if the diseased tissue is carefully examined. The changes in the lungs as they appear to the naked eye vary considerably from case to case. Thus in one animal the lungs were affected as in ordinary bronchopneumonia as to the location, extent, and appearance of the disease process. The affected lobes had a dark-red flesh appearance, with yellowish areas sprinkled in here and there. (See Pl. XLI, figs. 1, 2.) These latter areas were the seat of multiplication of the actinomyces fungus. In another case, of which only a small portion of the lungs was sent to the laboratory, they were completely transformed into a uniformly grayish ma.s.s, very soft and pulpy to the touch, and appearing like very soft and moist dough. (Pl. XLI, fig. 3.) The actinomyces grains were exceedingly abundant in this tissue, and appeared when the tissue was incised as minute sulphur-yellow grains, densely sprinkled through the tissue, which readily came away and adhered to the knife blade. In still another case a portion of the lung tissue was converted into large, soft ma.s.ses from 1 to 3 inches in diameter, each partly inclosed in very dense connective tissue. These soft, grayish-yellow ma.s.ses likewise resembled moist dough in their consistency, and the actinomyces grains, though neither very distinct nor at all abundant, were easily fished out and identified as such. A portion of this growth, which was as large as a child's head, was converted into an abscess filled with creamy semiliquid pus.

This case differed from the preceding in that all appearance of lung tissue had disappeared from the diseased ma.s.s. Only on the exterior the lung tissue could be recognized, although even there it had been largely converted into very dense, whitish connective tissue inclosing the fungoid growth. In the other case the external form of the lung and the shape and outline of the lobules were preserved, but the lung tissue itself was not recognizable as such. In the case first mentioned the changes were still less marked, and actinomycosis would not have been suspected by a simple inspection. These few ill.u.s.trations suffice to show that actinomycosis of the lungs may appear under quite different forms, and that the nature of the disease can be accurately determined only by finding the fungus itself.

Rarely actinomycosis attacks the body externally in places other than the head and neck. Crookshank describes the case of a bull in which the flank was attacked and subsequently the s.c.r.o.t.u.m became diseased. A large portion of the skin of the flank was destroyed and covered with a leathery crust.

When this was pulled away the pus beneath it showed the actinomyces grains to the naked eye.