SPECIAL REPORT ON DISEASES OF CATTLE TEXT

[8] For fuller information see Farmers' Bulletin 1057, from which the directions here given are mainly derived. [9] The chemicals employed have no effect upon iron. They will, however, actively corrode zinc, tin, or solder; hence a soldered pail must be watched for leaks and is far inferior to a seamless pail, stamped from a single sheet of iron. A tinned pail is preferred to a galvanized one, but a plain iron seamless pail or an iron kettle should be obtained if possible. [10] Best done by previously determining by measurement the depth of 5 gallons of water in the kettle. Set the kettle exactly level and mark the depth on a stick held vertically on the center of the bottom. ANIMAL PARASITES OF CATTLE. By B. H. RANSOM, Ph. D., _Chief of Zoological Division, Bureau of Animal Industry._ The animal parasites of cattle comprise more than a hundred different species, belonging to various groups of the animal kingdom. Fortunately not all these parasites occur in this country--many are uncommon, and many are comparatively harmless. Some forms, however, occur frequently, and some are of distinct importance to the American stockman on account of the damage for which they are responsible. It is these parasites particularly which will be referred to in the present article, and although some forms are discussed which are rare or apparently of little economic importance, most of the minor and unusual parasites and species not found in this country have been omitted from consideration. FLIES.[11] Of the various species of flies which infest cattle some are injurious on account of the annoyance, pain, and loss of blood due to their bites, and sometimes also on account of diseases or parasites which are thus transmitted from the blood of diseased animals to that of healthy cattle, while others, which in the winged adult state do not bite, are injurious because they live parasitic on cattle during their larval stages. _Remedies for flies._[12]--Most remedies used for protecting cattle from the attacks of flies have to be applied frequently, and few, if any, will keep flies away for more than a day or two following their application. The numerous proprietary fly repellents to be found on the market are usually more expensive, and often less efficacious than homemade mixtures. At the Minnesota experiment station rancid lard 1 pound and kerosene one-half pint, mixed thoroughly until a creamy mass forms, was found to give excellent results as a fly repellent, lasting for two or three days, when rubbed not too thickly with a cloth or with the bare hand over the backs of cows. Mixtures of cottonseed oil and pine tar containing from 10 to 50 per cent of the latter substance were found by investigations in the Bureau of Animal Industry to have a marked repellent action against flies when applied lightly every day. A too free application of tar mixtures and other preparations containing phenols is liable to cause poisoning; hence care should be observed in this regard. Jensen (1909) recommends the following formula, which is said to protect cows for a week: Common laundry soap 1 pound. Water 4 gallons. Crude petroleum 1 gallon. Powdered naphthalin 4 ounces. Cut the soap into thin shavings and dissolve in water by the aid of heat; dissolve the naphthalin in the crude oil, mix the two solutions, put them into an old dasher churn, and mix thoroughly for 15 minutes. The mixture should be applied once or twice a week with a brush. It must be stirred well before being used. THE STABLE FLY (STOMOXYS CALCITRANS).[13] This fly very closely resembles the house fly, but, unlike the latter, it is a biting fly. It is common about stables and often enters dwellings, especially in cloudy weather. According to NoÈ, it is the agent of transmission of a parasitic roundworm of cattle (_Setaria labiato-papillosa_, see p. 529). This fly has been shown capable of transmitting anthrax from diseased to healthy animals, and under some conditions it may transmit surra, a disease caused by a blood parasite which affects horses, cattle, and other livestock. The annoyance suffered by cattle and horses from stable flies is much lessened if the stables are darkened. The screening of doors and windows, however, is preferable, as ventilation is not interfered with as it is in darkening stables. For milk cows coverings made from burlap (double thickness), including trouserlike coverings for the legs, may be used when the flies are very numerous and troublesome. One of the fly repellents mentioned above may be applied to cattle to protect them from stable flies. The Hodge flytrap fitted to the windows of dairy barns is a useful means of destroying stable flies. The United States Bureau of Entomology has found that a mixture of fish oil (1 gallon), oil of pine tar (2 ounces), oil of pennyroyal (2 ounces), and kerosene (1/2 pint) is fairly effective for a short time when applied lightly, but thoroughly, to the portions of animals not covered with blankets. The risk of poisoning with tar mixtures as already mentioned should be borne in mind in using this remedy. Care should be taken to apply it lightly. The stable fly breeds in moist accumulations of straw, chaff, cow or horse manure, and various fermenting vegetable substances. The dÈbris collecting in and under outdoor feed troughs, and the remains of straw stacks are favorable breeding places for the stable fly. Under the most favorable conditions about three weeks are required for development from the egg to the adult stage. The proper care of straw and the proper disposal of stable manure are very necessary in the control of stable flies. Straw stacks should be carefully built so as to shed rain, and loose straw or chaff should be scattered or burned. Straw not required for winter feed should be promptly disposed of by burning or scattering and plowing it under. Stable manure should be hauled out and scattered at regular intervals, preferably every three days, and the vicinity of stables should be kept free from accumulations of straw and hay that may become wet and serve as breeding places for the stable fly. THE HORNFLY (LYPEROSIA IRRITANS).[14] This fly, now found nearly everywhere in the United States, was introduced into this country from Europe about the year 1885. Hornflies have the habit of clustering about the base of the horn (fig. 2), whence the name by which they are popularly known. They do not damage the horn, and congregate there only to rest. In view of the general practice of dehorning cattle, the name hornfly is less distinctive than it once was. Moreover, hornflies rest on other parts of the body as well as the horns. When resting, their wings are held down close to the body (fig. 1); when feeding, their wings are held out nearly at right angles, ready for flight. They puncture the skin and suck blood, usually attacking the upper parts of the body, particularly those which are out of reach of the animal's head or tail. Unlike most flies, they remain on the animal more or less constantly, day and night. Owing probably to the irritation and annoyance caused by these flies, cattle often do not thrive as they should during seasons when the flies are numerous. The hornfly has also been charged with transmitting diseases, such as anthrax. [Illustration: PLATE XLIV. NORMAL SPLEEN AND SPLEEN AFFECTED BY TEXAS FEVER. Fig. 1. SPLEEN OF AN ACUTE, FATAL CASE OF TEXAS FEVER. Fig. 2. SPLEEN OF HEALTHY STEER.] [Illustration: PLATE XLV. TEXAS FEVER.] [Illustration: PLATE XLVI. THE CATTLE TICK (MARGAROPUS ANNULATUS), THE CARRIER OF TEXAS FEVER.] [Illustration: PLATE XLVII. THE CATTLE TICK (MARGAROPUS ANNULATUS). Figs. 1 and 2 DORSAL AND VENTRAL VIEWS OF MALE. Figs. 3 and 4 DORSAL AND VENTRAL VIEWS OF REPLETE FEMALE. (GREATLY ENLARGED.)] [Illustration: PLATE XLVIII. PORTION OF A STEER'S HIDE, SHOWING THE TEXAS-FEVER TICK (MARGAROPUS ANNULATUS) OF THE UNITED STATES. NATURAL SIZE. ORIGINAL.] [Illustration: PLATE XLIX. FIG. 1.--TICK-INFESTED STEER.] FIG. 2.--DIPPING CATTLE TO KILL TICKS.] [Illustration: PLATE L. FACSIMILE OF POSTER USED IN TICK ERADICATION WORK.] The fly lays its eggs in freshly dropped cow manure. They hatch in about 24 hours, and the larvÊ or maggots in four or five days develop to the pupal stage, which lasts a week or 10 days. From the pupal stage the mature fly emerges. The entire process of development from the deposition of the egg to the appearance of the mature fly therefore may be completed in two weeks, or even in a shorter time. To protect cattle from attacks of the hornfly they may be treated with one of the remedies mentioned above (p. 502). Dipping cattle in a vat provided with splashboards set at the proper angle destroys most of the hornflies present on the animals. Unless the splashboards are used all but a few of the flies succeed in escaping as the cattle plunge into the bath and later return to them. Scattering the droppings of cattle with a shovel, or with brush dragged over pastures, in order to insure the rapid drying of the manure and consequent destruction of the larvÊ, is, when practicable, an efficient means of reducing the number of these flies. [Illustration: FIG. 1.--Hornfly (_Lyperosia irritans_) in resting position. Enlarged. (From Bureau of Entomology.)] [Illustration: FIG. 2.--Hornflies (_Lyperosia irritans_) on cow horn. (From Bureau of Entomology.)] BUFFALO GNATS. These small flies, also known as black flies, are about one-eighth of an inch long and have a characteristic "humped" back (fig. 3). They breed in running water and appear in swarms during spring and summer, often in enormous numbers, causing great annoyance to stock and human beings, on account of their bites and their entrance into the eyes, nose, mouth, and other openings of the body. Their bites appear to be poisonous, and in seasons especially favorable to the gnats heavy losses of horses and cattle often occur. Buffalo gnats are more troublesome in bright, sunny weather than when it is cloudy, and animals which have not shed their winter coats suffer more from their attacks than those with smooth coats. Cattle kept in darkened stables are not molested. The application of one of the fly repellents already mentioned (p. 502) may help to protect animals from buffalo gnats. The burning of smudges is also a useful means of protecting stock from the attacks of these flies. [Illustration: FIG. 3.--Buffalo gnat. Enlarged. (From Bureau of Entomology.)] SCREW WORMS.[15] Screw worms (fig. 4) are the maggots of a fly (_Chrysomyia macellaria_), so called from their fancied resemblance to a screw. The adult fly (fig. 5) is about one-third of an inch long, with a bluish-green body, red eyes, and with three dark longitudinal stripes on the back (thorax). Attracted by odors of decay, it deposits its eggs, 300 to 400 at a time, in cuts, sores, castration wounds, etc. The crushing of a tick on the skin commonly results in screw-worm infection at that point. The eggs hatch in a few hours and the larvÊ or maggots, or so-called screw worms, begin to burrow into the flesh and continue burrowing and feeding from three to six days, after which they leave the wound and crawl into the earth, there transforming into the quiescent pupal stage. This stage is completed in three to fourteen days. The mature flies then emerge from the pupal envelope and are soon ready for egg laying. From two to three weeks are therefore required for the entire life cycle, although under certain conditions it is possible for the fly to undergo its full development in as short a time as seven days, and on the other hand as long as a month is often required. Besides cattle, the screw-worm fly attacks sheep, horses, dogs, and man. In the case of hogs it is generally the ears which are affected. The fly also breeds in dead animals, and all carcasses should therefore be buried deeply or burned. The complete destruction of all dead animals by burning has been found by the Bureau of Entomology to be by far the best method of controlling screw worms. _Treatment for screw worms._--For proper treatment an animal suffering from screw worms should be caught and thrown. Chloroform is then poured into the wound, taking care that it penetrates thoroughly into all the burrows of the screw worm, if necessary using a slender stick or a small bunch of twisted hay as a probe. The animal should be held for several minutes in order to insure the continued action of chloroform. Instead of chloroform, gasoline may be used, and carbon tetrachlorid is said by some authorities to give good results. Finally, the dead or dying maggots may be removed with forceps, the wound washed with a weak carbolic or cresylic acid solution, and painted with pine tar to reduce the chances of further attack by flies. Finally the wound should be dressed with a carbolic or cresylic ointment to promote healing and thus prevent further infection, or the wound may be painted with pine tar. Dipping in the arsenical dips used for destroying cattle ticks is a convenient method of treatment if many animals are involved. [Illustration: FIG. 4.--Screw worm (larva of _Chrysomyia macellaria_). Enlarged. (From Bureau of Entomology.)] [Illustration: FIG. 5.--Screw-worm fly (_Chrysomyia macellaria_). Enlarged. (From Bureau of Entomology.)] GRUBS, WARBLES, BOTS. Ox warbles are whitish or, when full grown, dark-colored grubs or maggots that develop from the eggs deposited on the hairs of cattle by certain flies known as warble flies. In the United States there are two species of ox-warble flies, technically known as _Hypoderma lineatum_ and _Hypoderma bovis._ These flies somewhat resemble bees in their general appearance, but like all flies have only two wings. The first named, _H. lineatum_, is commonly called the heel fly and is more generally distributed over the United States than the other species. The tail has a distinctive reddish-orange color and the legs are rough and hairy. This fly commonly deposits its eggs about the coronet, whence the name of heel fly, and on the fetlocks, knees, and hocks. When cattle are resting, eggs are deposited along the line of contact of the body with the soil. Cattle are frequently indifferent to the activity of this fly in depositing its eggs. Commonly 8 to 10 eggs, sometimes as many as 14, are attached to a single hair. In the United States the other warble fly, _H. bovis_, has been found only in the North (New England, New York, Pennsylvania, Maryland, Michigan, Iowa, Missouri, and Washington) and has not yet been found in the Southern States. The tail is orange-yellow, lighter in color than that of the other species, and the legs have but few hairs. This fly commonly deposits its eggs on the outside of the hind quarters and above the fetlocks when the animals are moving, or lower down if they are quiet. Cattle are usually much disturbed by the activity of this fly and not infrequently appear terror stricken. The eggs are attached singly, one egg to a hair near its base. The eggs of the warble flies hatch as a rule in about a week, the time varying with local conditions. The young warble is about 1 mm. (1/25 inch) long. It crawls to the base of the hair and burrows into the hair follicle. The entrance of the larvÊ frequently causes sudden appearance of swellings. The larvÊ of _H. bovis_ in entering the skin rarely cause a flow of serum or pus formation, but those of _H. lineatum_ commonly cause a considerable flow of serum with pus formation resulting in a matting of the hair on affected areas of the skin. The warbles after penetrating the skin migrate through the body and ultimately reach the backs of the cattle, _H. lineatum_ usually appearing there in northern latitudes about the middle of December and _H. bovis_ about a month later. During their migrations, before they reach the back, the young warbles spend a considerable period in the walls of the esophagus, or gullet, and may be found in this location as early as August 15. During the fall and winter a large proportion of the gullets of cattle that are slaughtered are found to be infested with warbles, and are known as grubby gullets or weasands in the packing houses. When the warbles first appear in the back they are about 3/5 inch long. They cause swellings about the size of pigeons' eggs, each swelling having a small hole in the center, which has been punctured in the skin by the warble to enable it to breathe. Through this hole the warble leaves the back of the cow when it has completed its parasitic stage of development, at which time it measures nearly an inch in length. The full-grown larvÊ begin to leave the backs of the cattle early in the year, and in northern latitudes the last leave before the middle of July. After leaving the backs of the cattle they burrow into the ground, lie quiescent for about a month, and become transformed into mature flies. In northern latitudes the mature flies of the species _H. lineatum_ may be observed during April and May, and those of the other species during June and July. The damage caused by warbles includes injury to stampeding cattle frightened by the fly, decreased milk flow and diminished growth in infested animals, and injury to hides, the last item being especially serious. _Treatment._--The best method of control known at present is to extract the warbles from the backs of cattle and kill them. If they are almost ready to leave the cattle, they may be squeezed from the backs with the fingers. Forceps are useful in removing the warbles, but it is important to be careful in extracting warbles not to crush them, as the body juices of these parasites are sometimes poisonous to cattle if absorbed into their circulation. In the South herds may be examined in November or early in December and once a month during the next two or three months. In the North the first examination may be made six weeks to two months later, with two or, better, three following examinations at intervals of a month. If this procedure is carefully carried out there will be a noticeable diminution of warbles the following year, and if persisted in the warble can be almost if not completely eradicated. Where an entire community follows up the practice of removing and destroying warbles, the results are highly beneficial. As a result of recent studies by various investigators it appears that the tiny grubs, newly hatched from the eggs, may gain entrance to the body by penetrating directly through the skin. Many observers, however, have held that the eggs or newly hatched larvÊ are taken into the mouth by the cattle licking themselves. It is possible, as in the case of several other parasites, that both modes of infection may occur and that the larvÊ may gain entrance to the body either by penetrating the skin or by being swallowed. From the evidence at present available it seems likely that the usual mode of entrance is through the skin. Irrespective of the mode of infection, the larvÊ evidently wander extensively through the tissues of the body, developmental stages being found in considerable numbers in the wall of the esophagus during the fall of the year. They have also been found in the spinal canal and in various other locations. Finally, about January they appear beneath the skin of the back, forming the well-known swellings. The posterior end of the grub is near the small opening in the hide, through which the grub breathes and discharges its excrement, and through which, when its development is complete, it finally escapes. The anterior end of the grub is at the bottom of the tumor, where the mucus collects upon which it feeds. By spring or early summer the grub is full