FOOTNOTES:
[4] These membranes comprise the smooth, very delicate, glistening lining of the large body cavities. In the thorax the serous membrane (pleura) covers the ribs and diaphragm as well as the whole lung surface. In the abdomen a similar membrane (peritoneum) lines the interior of the cavity and covers the bowels, liver, spleen, etc.
[5] Hogs are subject to actinomycosis.
[6] The distribution of Government blackleg vaccine was discontinued July 1, 1922.
[7] Only a general outline of methods of eradication will be given here. For detailed information, including directions for the construction of dipping vats and for the preparation of dips, the reader is referred to Farmers' Bulletin 1057, which may be obtained free upon application to the Department of Agriculture, Washington, D. C.
[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 Noé, 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 (½ 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 débris 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]
Fig. 1.—Hornfly (Lyperosia irritans) in resting position. Enlarged. (From Bureau of Entomology.)
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.
The fly lays its eggs in freshly dropped cow manure. They hatch in about 24 hours, and the larvæ 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 larvæ, is, when practicable, an efficient means of reducing the number of these flies.
Fig. 2.—Hornflies (Lyperosia irritans) on cow horn. (From Bureau of Entomology.)
BUFFALO GNATS.
Fig. 3.—Buffalo gnat. Enlarged. (From Bureau of Entomology.)
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.
SCREW WORMS.[15]
Fig. 4.—Screw worm (larva of Chrysomyia macellaria). Enlarged. (From Bureau of Entomology.)
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 3. 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 larvæ 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.
GRUBS, WARBLES, BOTS.
Fig. 5.—Screw-worm fly (Chrysomyia macellaria). Enlarged. (From Bureau of Entomology.)
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 larvæ frequently causes sudden appearance of swellings. The larvæ of H. bovis in entering the skin rarely cause a flow of serum
Fig. 6.—The warble fly (Hypoderma lineatum): a, adult female; b, eggs attached to a hair, × 25; c, larva as seen in egg; d, larva from esophagus of an ox; e, later stage of larva from beneath the skin of the back; f, larva at the stage when it leaves the back of cattle and falls to the ground—all enlarged (after Riley).
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 larvæ 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 larvæ 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 larvæ 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 larvæ 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 grown and forces its way out of the skin, falling to the ground, into which it burrows for a short distance and transforms into the pupal stage. In about a month the mature fly emerges.
It has lately been discovered that a second species of warble fly (Hypoderma bovis) common in Europe is of not uncommon occurrence in Canada and the northern part of the United States, whereas it was formerly supposed that the ox warbles of this country were all of the one kind. The general appearance, life history, and effects of the European species are much the same as those of the American form.
Grubs weaken cattle, cause them to fall off in flesh and milk, and decrease the value of the hide. The beef in the immediate vicinity of a grub becomes slimy and of a greenish color, and is known to the butchers as "licked beef."
The total loss to this country on account of the warble fly is estimated at $35,000,000 to $50,000,000 a year, at the least, and may amount to considerably more.
Treatment for warbles.—During the winter and spring examine the cattle for the presence of warbles. By passing the hand over the backs of the animals the swellings marking the location of the grubs may be readily found. Pressure properly applied to the swellings will cause the grubs to "pop out" if they have reached a late stage of development. They may be more easily removed by means of slender forceps inserted into the opening of the warbles, and a still more certain method of removing them, particularly if the lumps are still very small, is to cut into the swellings with a sharp knife or bistoury, after which they may be pressed out. Care should be taken to crush all grubs removed, so as to prevent the possibility of their further development and transformation into flies. In order that none may escape it is advisable to examine the cattle every two weeks during the late winter and spring, at each examination removing the grubs which have developed sufficiently to cause perceptible swellings.
Another method of treatment is to force grease or oil into the openings of the warbles, which kills the grubs. This method is less certain than that of removing the grubs, and has the further objection that the dead grubs remain beneath the skin.
Cattle may be treated during the summer with fly repellents ([p. 502]) to keep off the warble flies. The efficacy of repellents against these flies is probably, however, not very great.
In localities where the character of the cattle industry is such as to render practicable the systematic examination of cattle and the removal of the grubs—that is, where the herds are comparatively small and subject to the close supervision of the owners—it is possible, by the exercise of a little care and with very little effort on the part of the cattle owners, provided they work together, each doing his share by seeing to the removal of grubs from his own cattle, so that as few as possible survive to transform into flies, to reduce the number of grubs within one or two seasons almost, if not entirely, to the point of extinction.
Investigations not yet completed indicate that grub eradication may sometimes be accomplished by the use of arsenical dips, which are extensively used at the present time for destroying cattle ticks. (See [p. 497].) It is possible that the destructive action of arsenical dips upon warbles is more or less dependent upon the fact that arsenic is stored up in small quantities in and upon the skin of cattle that are repeatedly dipped in arsenical dips. The arsenical dip appears to act, not upon the well-developed grub beneath the skin, but upon the eggs or the newly hatched larvæ, probably the latter. Accordingly the dipping of cattle to destroy grubs should be carried out during the fly season and repeated treatments should be given every two or three weeks, as in dipping cattle to eradicate ticks.
LICE.[16]
Cattle in the United States are commonly infested with three species of lice, two of them sucking lice (Hæmatopinus eurysternus, the short-nosed cattle louse, and Linognathus vituli, the long-nosed cattle louse), commonly known as blue lice, and one biting louse (Trichodectes scalaris), commonly known as the red louse.
Fig. 7.—Short-nosed blue louse (Hæmatopinus eurysternus) of cattle. Enlarged. (From Bureau of Entomology.)
The blue lice (figs. 7 and 8) suck the blood of cattle and are more injurious than the red lice (fig. 9). Unless very abundant the latter cause little injury. If numerous they irritate and worry their host probably more by their sharp claws than by their bites, as their food seems to consist entirely of particles of hair and dead skin.
Fig. 8.—Long-nosed bluelouse (Linognathus vituli) of cattle. Enlarged. (From Bureau of Entomology.)
Cattle lice reproduce by means of eggs or nits (fig. 10) which they fasten to the hair. The blue lice infest chiefly the neck and shoulders; red lice, when present, may be found almost anywhere on the body, but are usually most numerous on neck, shoulders, and at the root of the tail.
On account of the itching caused by the lice, infested cattle rub against posts, trees, etc., and lick themselves, the hair sometimes coming out and the skin becoming thickened so that mange may be suspected.
Treatment for lice.—Cattle may be treated for lice by means of hand applications, spraying, or dipping. Dusting powders sold under various trade names are of value in helping to hold lice in check when the weather is too cold for dipping or spraying. The application of greases and insecticidal liquids by hand is fairly effective and practicable in cases in which there are only a few animals to be treated. The following remedies have proved effective when applied by hand, the treatment being repeated if necessary in about 16 days: (1) Cottonseed oil and kerosene, equal parts; (2) kerosene, ½ pint, mixed with lard, 1 pound; (3) crude petroleum; (4) any of the dips recommended for use in dipping, and diluted in the same proportions as for dipping. Oils or greases should not be used in very warm or very cold weather. The remedies mentioned may be applied with a brush or a cloth. They should be distributed in a thin, even coating over the surface of the body, taking care that there is no excess quantity at any point.
In spraying, any of the dips recommended for lice, properly diluted, are applied by means of a spray pump over the entire body. Thorough wetting of the skin and hair is important, and a second treatment should be given 15 or 16 days later.
Fig. 9.—Red louse (Trichodectes scalaris) of cattle. Enlarged. (From Bureau of Entomology.)
When a considerable number of animals are to be treated the most satisfactory method of destroying lice is by the use of a dipping vat. Two dippings should be given 15 or 16 days apart. Dipping in the fall is good insurance against risk of loss from lice during the winter. All animals in the herd should be treated regardless of the number showing infestation. Either coal-tar-creosote or nicotin dips may be used. These are sold under various trade names. The directions for dilution given by the manufacturer should be carefully followed. As coal-tar-creosote dips do not mix well with all kinds of water, they should be tested with the water to be used for making the solution by mixing some of the dip in the proper proportions with the water in a clean and clear-glass bottle or jar. If an oily layer or mass of globules collects either at the top or the bottom of the mixture after standing an hour, the dip is not suitable for use with that kind of water. Imperfectly mixed coal-tar-creosote dips are liable to poison animals even when not used in stronger solutions than that recommended by the manufacturers, and are also likely to be inefficacious.
Fig. 10.—Egg of short-nosed blue louse (Hæmatopinus eurysternus) attached to a hair. Enlarged. (From Bureau of Entomology.)
The lime-sulphur dip, which is highly efficacious as a mange remedy, is of little value for destroying lice, especially blue lice. The arsenical dip used in tick eradication is a good louse remedy, but its use is not advisable on account of its poisonous nature, except under the supervision of capable persons who know how to use it and what precautions to take.
MANGE, ITCH, SCAB. [17]
Cattle are subject to four kinds of mange, of which common mange or psoroptic mange is the most important.
Fig. 11.—Mite which causes psoroptic scab of sheep. Enlarged about 100 times. The mite of psoroptic cattle mange is almost identical in appearance.
PSOROPTIC MANGE.
Psoroptic mange of cattle is caused by small mites (fig. 11) which multiply rapidly and are spread from diseased to healthy cattle by bodily contact, or by pens, stables, railroad cars, etc., recently occupied by mangy cattle. The mites attack the skin and cause it to become thickened and covered with crusts and scabs, with a consequent loss of hair. Intense itching accompanies the disease, and affected cattle are more or less constantly rubbing and licking themselves. Psoroptic mange commences at the root of the tail, or on the neck, or withers, and gradually extends over the back up to the head, over the sides, and may finally affect nearly the entire body except the legs. In serious cases the skin may become ulcerated; the animals are greatly weakened and emaciated, and finally die. By taking scrapings from the edges of scabby patches and placing them on a piece of black paper in a warm place the mites may be seen as tiny white objects crawling over the paper, more distinctly if a magnifying glass is used. Mange may be confused with lousiness, ringworm, or with any condition in which there is itching or loss of hair, but if mites are found there is no question of the diagnosis. The disease is worse during cold, wet weather. Mangy cattle when on good pasture during the summer often seem to recover, but in the fall the disease again appears in a severe form.
Treatment.—The most generally used and most satisfactory method of treating cattle mange consists in dipping the animals in a vat filled with a liquid of such nature that it will kill the parasites without injuring the cattle. Vats for dipping cattle are built of wood, stone, or concrete, and vary in length from 30 to 100 feet or more. They vary in width from 3 to 7 feet at the top and 1½ to 3 feet at the bottom, and the depth may be from 7 to 10 feet. A narrow chute through which the cattle are driven leads to one end of the vat, where a steep slide pitches the cattle into the dipping fluid, through which they swim, and climb out of the vat at the other end, which is built sloping and provided with cross cleats to give the animals a foothold. A draining pen with floor sloping back toward the vat is generally provided. The dip should be used warm, 100° to 105° F., and the cattle should be held in the vat for two minutes to insure thorough action of the dip. The head of each animal should be ducked at least once. Care should be taken that the vat contains a sufficient depth of fluid to swim the animals to be dipped. The dipping fluid may be heated from a steam boiler by pipes or hose, or water heated in large iron cauldrons or tanks may be used for charging the vat, and hot water with a proper quantity of dip added from time to time as the dipping fluid becomes cool.
If crude-petroleum dips are used, one dipping is usually sufficient, and the dip is used cold. Crude-petroleum dips are rarely used for common mange, but are of special value for sarcoptic mange, which is cured with difficulty by the ordinary dips. In the treatment of ordinary mange with lime-sulphur or nicotin dips two dippings are necessary, the second dipping being given 10 to 14 days after the first. The second treatment is necessary to kill the few parasites which sometimes escape at the first treatment, either in the egg stage or as fecundated females.
LIME-SULPHUR DIP.
The lime-sulphur dip is made in the proportion of 12 pounds of unslaked lime (or 16 pounds of commercial hydrated lime—not air-slaked lime), 24 pounds of flowers of sulphur, and 100 gallons of water.
Directions for preparing 100 gallons of dip.—Weigh out the lime, 12 pounds (or hydrated lime, 16 pounds), and sulphur, 24 pounds. Place the unslaked lime in a shallow, water-tight box similar to a mortar box, or some other suitable vessel, and add water enough to slake the lime and form a lime paste or lime putty. Sift into this paste the flowers of sulphur and stir well; then place the lime-sulphur paste in a kettle, boiler, or tank containing 30 gallons of water, the water being first heated nearly to the boiling point. Boil the mixture for two hours at least, stirring frequently; add water occasionally to maintain the original quantity. Allow the mixture to settle in the tank or draw the entire contents of the kettle or boiling tank into a large tub or barrel placed near the dipping vat and provided with a bunghole about 4 inches from the bottom, and then allow ample time to settle—from two to three hours or more if necessary. When fully settled, draw off the clear liquid into the dipping vat, taking care not to allow any of the sediment to accompany it, as the sediment is liable to render the dip unnecessarily caustic. The clear liquid thus obtained requires only the addition of sufficient clear warm water to bring the total up to 100 gallons. Flowers of sulphur must be used and the lime must be of good quality.
The dipping bath should be used at a temperature of 100° to 105° F., and for official dippings must be maintained at all times at a strength of not less than 2 per cent of "sulphid sulphur" as indicated by the Bureau of Animal Industry field test for lime-sulphur baths.
NICOTIN DIP.
The nicotin dip is made with sufficient extract of tobacco, or nicotin solution, to give a mixture containing not less than five one-hundredths of 1 per cent nicotin and 2 per cent flowers of sulphur. Sufficient nicotin would therefore be furnished for 96 gallons (about 800 pounds) of dip by 1 pound of a 40 per cent solution of nicotin. The formula for this dip would be: Nicotin, four-tenths of a pound; flowers of sulphur, 16 pounds; water, 96 gallons.
To calculate how much nicotin solution or extract of tobacco should be used for 96 gallons of water, divide the quantity of nicotin required in the dip by the proportion of nicotin in the extract. For example, suppose the nicotin solution contains 25 per cent nicotin, we have 0.40 ÷ 0.25 = 1.6. Therefore in this case it would require 1.6 pounds of nicotin solution for the 96 gallons of dip. Or, if a tobacco extract is used, having, for example, 2.4 per cent of nicotin, the formula would be as follows: 0.40 ÷ 0.024 = 16.66, and therefore 16.66 pounds would be required for 96 gallons of dip. Do not use any preparation the strength of which is not given on the outside of the package.
In preparing these dips the nicotin solution and sulphur should be mixed together with water before adding them to the water in the dipping vat. On no account should the dip be heated above 110° F. after the nicotin solution is added, as heat is liable to evaporate the nicotin and weaken the dip.
For official dippings the dipping bath should be used at a temperature of 100° to 105° F. and at all times must be maintained at a strength of not less than five one-hundredths of 1 per cent nicotin as indicated by a field test approved by the Bureau of Animal Industry.
A homemade nicotin dip may be prepared as follows:
For each 100 gallons of dip desired, take 21 pounds of good, prepared tobacco leaves; soak the leaves in cold or lukewarm water for 24 hours in a covered pot or kettle; then bring the water to near the boiling point for a moment, and, if in the morning, allow the infusion to draw for an hour; if in the evening, allow it to draw overnight; the liquid is next strained (pressure being used to extract as much nicotin as possible from the wet leaves) and diluted to 100 gallons per 21 pounds of tobacco. This dip should be used as fresh as possible, as it contains a large amount of organic material which will soon decompose.
CRUDE-PETROLEUM DIPS.
Crude-petroleum dips, which are valuable for the treatment of sarcoptic mange, are not often used for the treatment of psoroptic mange or of chorioptic mange, oily dips being liable to injure animals, especially if they are moved rapidly soon after treatment, if they are exposed to bright sunshine, or if they become chilled. Besides unprocessed crude petroleum, processed petroleum from which the gasoline and other light hydrocarbons have been removed may be utilized in the treatment of cattle for mange, particularly sarcoptic mange. There are a number of proprietary brands of crude-petroleum dips on the market, consisting of processed crude petroleum with other substances added, mainly lighter oils to give the dip a suitable consistency. In dipping cattle in crude-petroleum dips fill the vat with water to within 1 foot or 18 inches of the dip line and then add the oil until the surface is flush with the dip line. The oil floats on the water, and as the animals pass through the vat their bodies become coated with oil.
CHORIOPTIC MANGE.
Chorioptic mange, due to a species of mite different from that causing common cattle mange, is confined almost entirely to the region at the root of the tail and if not treated may persist for years. The treatment is the same as for psoroptic mange.
SARCOPTIC MANGE.
Sarcoptic mange, frequently called "barn itch," is caused by a mite very similar to that which causes itch in human beings. It commonly affects the head and neck, but may also occur on various other parts of the body. Bulls are particularly liable to be affected with this form of mange. Cattle may become infected not only from other cattle, but also from horses, goats, dogs, sheep, and hogs. As a rule sarcoptic mange in any species of animal, if acquired from an animal of another species, is likely to run a short course and tend toward a spontaneous recovery.
The treatment likely to be most efficacious is that of dipping in a crude-petroleum dip, one treatment as a rule being sufficient. If lime-sulphur dip is used, four or five successive treatments, or even more, at weekly intervals, may be necessary before a cure is effected.
DEMODECTIC MANGE.
Demodectic mange, which is caused by a small parasite that lives in the hair follicles, causing pustules, especially on the neck and shoulders, occurs occasionally among cattle in this country and is of importance on account of the injury to the hide. When tanned, hides infested by this parasite are pitted, the pits, in some cases, being so deep that they form holes. No practicable treatment is known for this disease.
TICKS.[18]
About 10 species of ticks have been reported as parasites of cattle in the United States. The most common and most important is the species known as Margaropus annulatus, which transmits Texas fever. Information concerning this tick and Texas fever has been given elsewhere in this volume ([p. 475]).
The spinose ear tick (Ornithodoros megnini) is frequently found in the ears of cattle in the western part of the United States, and is of common occurrence also in the ears of horses, dogs, cats, etc.
When its parasitic stage of development is completed the ear tick leaves its host. Mating between the sexes occurs after the ticks have cast their skins following the abandonment of their host. They usually crawl up some distance from the ground and secrete themselves in cracks and crevices in trees, walls of buildings, etc., where the females deposit their eggs.
After the eggs hatch, the larval ticks, which emerge from them, when they succeed in finding a host, enter the ears and gradually develop to the stage at which they are ready to leave the host animal. The females may live several months, or even years, if they do not find mates. After mating they may deposit their eggs intermittently. Hatching of the eggs may occur as early as 10 days after deposition. The larvæ may live for 80 days without a host. The parasitic period has been observed to vary from about two to about seven months.
Treatment.—On account of their habits and great vitality and their occurrence in various kinds of animals besides cattle, complete eradication is a difficult problem. The only effective treatment known is to introduce directly into the ear passages a remedy that will kill the ticks. Later, of course, the cattle may become reinfested from exposure to infested ranges or inclosures. The following mixture, however, in addition to killing the ticks in the ears, will protect against reinfestation for about 30 days: Ordinary commercial pine tar, two parts; cottonseed oil, one part—in each case by volume. Animals to be treated are confined in a chute, and the mixture is injected into the ears with a syringe, after the wax and other débris in the ears have been cleaned out with a wire probe that has an eyelet at one end. Further information concerning ear ticks and the details of their treatment is given in Farmers' Bulletin 980.
BLOODSUCKERS OR LEECHES.
Fig. 12.—Portion of the wall of the first stomach with conical flukes attached.
These worms are sometimes taken up by cattle when drinking from ponds. They may attach themselves to the inner surface of the mouth or nose, and sometimes reach the upper part of the windpipe or of the gullet. Bleeding at the mouth or nose may be noticed, the membranes where the leech is attached are liable to be swollen and congested, and as a result of the loss of blood a condition of anemia may result.
Treatment.—If the worm can be reached it may be destroyed by cutting it in two with a pair of scissors, or it may be removed with forceps or with the fingers after wrapping a towel around the hand so that the worm can be held without slipping. Fumigation with tobacco or tar may cause the worm to release its hold if it can not be removed by other means. Ponds may be rid of infestation with bloodsuckers by the introduction of eels.
PARASITES OF THE STOMACH.
Fig. 13.—Twisted stomach worms (Hæmonchus contortus). Outlines showing natural size of male (above) and female.
The stomach of cattle consists of four compartments, of which the first and fourth are most likely to be the seat of parasitic infestation. The first stomach, or paunch, contains large numbers of minute parasites known as protozoa, which are too small to be seen with the naked eye. These small organisms apparently are in no way injurious. A species of fluke (Paramphistomum cervi or a closely related species) is occasionally found in North American cattle, especially grass-fed cattle, attached to the inner surface of the first stomach (fig. 12). This worm is about one-half inch long, and somewhat conical in shape; hence the name, conical fluke, by which it is sometimes known. Although this parasite has been accused of producing serious effects, it is generally considered harmless.
Several species of roundworms may occur in the fourth stomach. Two of these are of special importance.
THE TWISTED STOMACH WORM (HÆMONCHUS CONTORTUS).
The twisted stomach worm (Hæmonchus contortus, figs. 13, 14, 15) is sometimes found in enormous numbers in the fourth stomach of cattle. Sheep, goats, and other ruminants may also be infested with it. Among the symptoms caused by this parasite may be mentioned anemia, loss of flesh, general weakness, dullness, capricious appetite, excessive thirst, and diarrhea. The anemic condition is seen in the paleness of the skin and mucous membranes of the mouth and eye, and in the watery swellings which often develop under the lower jaw ("poverty jaw"). If the fourth stomach of a dead animal is cut open and the contents carefully examined, the parasites, which are from ½ inch to 1¼ inches in length and about as thick as an ordinary pin, may be seen, if present in any considerable number, actively wriggling about like little snakes.
Fig. 14.—Twisted stomach worms (Hæmonchus contortus). Male (a), female (b), and egg (c). Enlarged.
Cattle become infected with these parasites by grazing on pastures on which infested cattle, sheep, or goats have grazed and scattered their droppings. The worms in the stomach produce a multitude of eggs (fig. 14c) of microscopic size, which pass out of the body in the feces. In warm weather these eggs hatch in a few hours. If the temperature is below 40° F., they remain dormant, and if below freezing, they soon die. The eggs are also killed by dryness; moisture, on the other hand, favoring their development. The larvæ which hatch from the eggs are microscopic in size, and, like the eggs, are, at first and until they have developed to a certain stage, very susceptible to freezing and drying. In very warm weather the larvæ complete their development, so far as they are able to develop outside the body, in two or three days. In cooler weather the time required for this development is longer, and at temperatures below 70° F. 10 days to several weeks may be necessary. The larvæ are then ready to be taken into the body. The eggs and early stages of the larvæ apparently do not develop if swallowed, and only the completed larval stage seems to be infectious. In this stage the larvæ migrate up grass stalks (fig. 15) or other objects, showing activity whenever the air is saturated with moisture; that is, during rains, fogs, and dews. When the air becomes dry and the moisture evaporates from the grass the young worms cease their activity, resuming their migrations when the air again becomes overladen with moisture. Larvæ which have developed to the infectious stage, unlike the eggs and early larval stages, are able to survive long periods of freezing and dryness. In two weeks to a month after the embryos are swallowed they reach maturity and begin producing eggs.
Fig. 15.—Larva of twisted stomach worm (Hæmonchus contortus) coiled on tip of grass blade. Enlarged.
Preventive treatment.—Preventive measures are important. As moisture favors the development of the embryos, high sloping ground is preferable for pastures. If low ground is used, it should be properly drained. The pasture should not be overstocked. Burning over the pasture will destroy most of the young worms on the grass and on the ground, and this means of disinfection under certain circumstances may be very advantageously used. The herd should be changed to fresh pasture as often as possible. Cattle should be supplied with water from wells, springs, or flowing streams, preferably in tanks or troughs raised above the ground. To a slight degree salt serves to protect cattle against infection with internal parasites, and plenty of it should therefore be kept accessible.
Affected animals should be isolated from the rest of the herd in hospital pens or pastures. A plentiful supply of nourishing feed is an important factor in enabling cattle to withstand the attacks of stomach worms and other intestinal parasites. The stabling of cattle, with the maintenance of clean and sanitary surroundings and liberal feeding, will often stop losses from internal parasites, even though no medicinal treatment is given.
Medicinal treatment.—In dosing animals for stomach worms it is advisable to treat not only the animals which are seriously affected, but the rest of the herd as well, since the parasites with which they are infested will remain as a source of reinfection to the others. The cattle should be removed to fresh pasture after treatment, if possible.
The animals to be treated should be deprived of feed for 12 to 16, or even 24, hours before they are dosed, and if the bluestone treatment is used should receive no water on the day they are dosed until several hours after dosing. In drenching, a long-necked bottle or a drenching tube may be used. In case the former is used the dose to be given may be first measured off, poured into the bottle, and the point marked on the outside with a file, so that subsequent doses may be measured in the bottle itself. A simple form of drenching tube (fig. 16) consists of a piece of rubber tubing about 3 feet long and one-half inch in diameter, with an ordinary tin funnel inserted in one end and a piece of brass or iron tubing 4 to 6 inches long, of suitable diameter, inserted in the other end. In use the metal tube is placed in the animal's mouth between the back teeth, and the dose is poured into the funnel, which is either held by an assistant or fastened to a post. The flow of liquid through the tube is controlled by pinching the rubber tubing near the point of union with the metal tube. It is important not to raise the animal's head too high on account of the danger of the dose entering the lungs. The nose should not be raised higher than the level of the eyes. The animal may be dosed either standing on all fours or lying on the side.
Fig. 16.—A drenching tube made from an ordinary tin funnel, a piece of rubber hose, and a piece of brass pipe.
The position on all fours is preferred by some authorities, who believe that more of the remedy is likely to reach the fourth stomach when the animal is dosed standing than when dosed in other positions.
Great care should be used in dosing to prevent the entrance of the liquid into the lungs, and in the preparation and administration of the remedy to avoid getting the solution too strong or the dose too large.
Bluestone, or copper sulphate, has been extensively used in South Africa in the treatment of sheep and cattle for stomach worms and is recommended by the colonial veterinary surgeon of the Cape Colony as the best and safest remedy. To prepare the solution take 1 pound (avoirdupois) of pure bluestone, powder it fine, and dissolve in 9½ gallons of warm water. It is better first to dissolve the bluestone in 2 or 3 quarts of boiling water, then add the remaining quantity of cold water, and mix thoroughly. This solution may be given to cattle in the following-sized doses:
| Calves | 3½ to 4 fluid ounces. |
| Yearlings | 6 fluid ounces. |
| Two-year-olds and over | 12 to 16 fluid ounces. |
In making up the solution only clear blue crystals of bluestone should be used. Bluestone with white patches or crusts should be rejected. It is especially important that the bluestone and water be accurately weighed and measured, and that the size of the dose be graduated according to the age of the animal.
The special value of medicated salts advertised under various trade names as preventives against worms is problematical. Commonly they contain little else than ordinary salt, the other substances being in such small quantity that their therapeutic effect is practically negligible. Definite evidence that they are more efficacious than plain salt is not yet available and their use is not recommended.
THE ENCYSTED STOMACH WORM (OSTERTAGIA OSTERTAGI).
Fig. 17.—Piece of lining of fourth stomach, showing cysts of the encysted stomach worm (Ostertagia ostertagi).
This parasite is as thick as a fine hair and less than half an inch in length. It lives in small cysts in the wall of the fourth stomach (fig. 17) and is also found free in the cavity of the stomach. When numerous, these parasites cause a thickening of the stomach wall and disturb its digestive functions. The symptoms caused by this parasite are very similar to those produced by the twisted stomach worm. The life history of the encysted stomach worm is not known in detail, but it is undoubtedly very much the same as that of the twisted stomach worm. The same measures as recommended above for preventing infection with the twisted stomach worm should be used. Medicinal treatment would seem to be of little use, owing to the protected position in which the parasite occurs.
INTESTINAL PARASITES.
TAPEWORMS.
Fig. 18.—A tapeworm (Moniezia planissima) which infests cattle.
Two species of tapeworms (fig. 18) are known to occur in the small intestine of American cattle. They sometimes grow to a length of several yards and to a breadth of three-fourths of an inch. Small portions of tapeworms, consisting of one or more segments, are occasionally seen in the droppings of infested cattle. The life history is not known, but the infectious stage is undoubtedly taken in with the feed or water, infection being spread by the eggs of the parasite contained in the feces of infested animals. The eggs are perhaps swallowed by some small creature (an insect, worm, or snail) which acts as an intermediate host, and which when accidentally swallowed by a cow while grazing or drinking carries with it into her stomach the infectious stage of the tapeworm.
Adult cattle do not seem to suffer much from infestation with tapeworms, but in calves these parasites may cause scouring and emaciation.
Treatment.—Medicinal treatment for tapeworms in cattle is usually unsatisfactory, but the bluestone treatment used for stomach worms and mentioned above ([p. 522]) sometimes expels tapeworms. Arsenic in doses of 1½ to 3 grains has been claimed to give good results in the treatment of calves for tapeworms. From results obtained at the Oklahoma Experiment Station in the treatment of tapeworms of sheep it would appear that the efficacy of the bluestone treatment against these parasites may be increased by the addition of tobacco. For use on cattle the bluestone and tobacco mixture may be prepared as follows: 13 ounces of snuff or powdered tobacco is soaked over night in about 8 gallons of water. To this decoction is added 1 pound of copper sulphate which has been dissolved in 2 or 3 quarts of boiling water. Sufficient water is then added to the mixture to make a total of 9½ gallons. The doses of this solution are the same as for the simple copper sulphate solution, described on [page 522], namely:
| Calves | 3½ to 4 | fluid ounces. |
| Yearlings | 6 | fluid ounces. |
| Two-year-olds and over | 12 to 16 | fluid ounces. |
ROUNDWORMS.
A large roundworm (Ascaris vitulorum) measuring 6 to 12 inches in length, sometimes found in the intestines of cattle, especially calves, may cause inflammation and occasionally rupture of the intestine. Infection occurs through the swallowing of the eggs of the parasite in feed or water which has been contaminated with the feces of infested cattle.
A number of species of small roundworms, varying in size from an eighth of an inch to an inch or more in length, occur in the intestines. Of these may be mentioned the hookworm (Bunostomum phlebotomum) and the nodular worm (Œsophagostomum radiatum). The former is about an inch long and is found in the small intestine. The latter is somewhat smaller and is found in the cecum and large intestine. Hookworms, when numerous, may cause anemia and other symptoms similar to those caused by stomach worms (see [p. 519]). The injury to the mucous lining of the intestine from the bites of hookworms may cause severe inflammation, and affords an avenue of infection with the germs of various diseases. The adult nodular worms apparently do not attack the wall of the intestine, but derive their nourishment from the intestinal contents. Several species of small, very slender roundworms (Trichostrongylus), less than a quarter of an inch in length, sometimes occur in the small intestine and fourth stomach, and a severe gastroenteritis, or inflammation of the stomach and intestines, has been attributed to them. One species of small roundworm (Cooperia punctata) burrows in the wall of the small intestine and causes caseous nodules in the mucous lining. This parasite sometimes occurs in very large numbers in the intestines of cattle in certain sections of the country, and apparently does considerable damage.
Nodular disease of the intestine, due to young nodular worms which burrow in the intestinal wall during a certain stage in their life history, sometimes apparently produces serious effects, particularly in young cattle, but commonly has little or no perceptible influence on the general health. It, however, often renders the intestine unfit for use as sausage casings, and as it is widely prevalent among cattle the loss from this source is considerable. The greenish or yellowish nodules with cheesy contents are frequently mistaken by the inexperienced for lesions of tuberculosis.
The life histories of the various small roundworms occurring in the intestines of cattle, so far as they have been worked out, are very similar to that of the twisted stomach worm as described on [page 519].
Treatment for intestinal roundworms.—The preventive measures are similar to those recommended in the case of the twisted stomach worm ([p. 521]). Medical treatment is generally not very satisfactory. According to the Oklahoma Experiment Station, the addition of 1 per cent of tobacco to the bluestone solution used in the treatment of stomach worms in sheep is effective in the removal of hookworms. The bluestone and tobacco mixture described on [page 524] may be of value in the treatment of hookworms in cattle. It is asserted by one author that 2 or 3 drams of rectified empyreumatic oil in a mucilaginous emulsion, followed the next morning with a purgative of 1 to 1½ pounds of sulphate of soda, will expel the large roundworms (Ascaris vitulorum).
PROTOZOA.
A number of species of protozoa have been reported as parasites of the intestines of cattle. To one species has been attributed a serious disease of cattle in Switzerland known as red dysentery, but so far comparatively few cases of this disease have been recorded in America. It is probably more common than is generally supposed. Calves particularly seem most likely to be affected.
FLUKES IN LIVER AND LUNGS.
Fig. 19.—The common liver fluke (Fasciola hepatica).
Two species of flukes occurring in the liver and lungs are known to affect cattle in the United States. These parasites are flat, leaf-like worms; one of them, the common liver fluke (Fasciola hepatica, fig. 19), is less than an inch in length, while the other, the large American fluke (Fasciola magna, fig. 20), is considerably larger when full grown. In their life history these flukes depend on snails as intermediate hosts. At a certain stage of development the young flukes leave the snails, become encysted on stalks of grass (fig. 21), or fall into drinking water, and finally may be swallowed by cattle. Stiles writes as follows:
Fig. 20.—The large American fluke (Fasciola magna).
Flukes may produce a serious, often fatal, disease, more especially in younger animals. The symptoms are somewhat similar to those produced by worms in the stomach. The first symptoms are generally overlooked, the disease not attracting attention until the appetite is diminished; rumination becomes irregular, the animals become hidebound, and the coat dull and staring. The staring coat is due to the contraction of the muscles of the hair follicles. The visible mucous membranes become pale, eyes become dull, there is running at the eyes, and the animal gradually becomes emaciated. As the disease advances the milk supply is lessened, fever appears, there is generally great thirst, but the appetite almost ceases; edematous swellings appear on the belly, breast, etc.; diarrhea at first alternates with constipation, but finally becomes continuous. The disease lasts from two to five months, when the most extreme cases succumb.
Most of the German cattle are said to be infested with liver flukes, but even when a large number are present the nourishment of the cattle is not disturbed. Thickening of the gall ducts, so that a so-called "Medusa's head" forms on the surface of the liver toward the stomach, appears in even well-nourished animals; even in cases of a cirrhosis of the liver it is seldom that any effect upon the cattle's health can be noticed, and so long as a portion of the liver tissue about twice the size of the fist remains intact, the nourishment of the animal may be comparatively good. It is rare that one sees a generalized edema in slaughtered cattle as a result of fluke invasion, and even in the heaviest infections of young cattle only emaciation is noticed.
Treatment.—Medicinal treatment is unsatisfactory. The disease may be prevented to a considerable extent by giving animals plenty of salt, and by introducing carp, frogs, and toads into infected districts; these animals destroy the young stages of the parasite and feed upon the snails which serve as intermediate hosts.
Fig. 21.—Portion of grass stalk bearing three encysted cercariæ of the common liver fluke (Fasciola hepatica). Enlarged.
The drainage of wet pastures and the avoidance of swampy lands for grazing purposes are important measures in the prevention of fluke diseases.
Railliet and others have recently recommended the application of lime to fluky pastures, having discovered that very weak solutions are destructive not only to fluke embryos but to snails. This application is to be made during the summer months at the rate of about 500 to 1,000 pounds of lime per acre. The same authors also recommend extract of male fern for the treatment of fluke disease. Moussu states that the average dose for cattle is 1 gram of the extract for each 10 kilograms of live weight; that is, 10 grams for a young animal weighing 100 kilograms (about 220 pounds) up to 50 grams as a maximum for large animals weighing 500 kilograms (about 1,100 pounds) or more. The extract is mixed with about 5 times as much non-purgative oil and the dose is administered each morning for five consecutive days two hours before the animal is allowed to feed after having been fasted over night. The extract of male fern used should have a guaranteed strength of 22 to 25 per cent of filicine and 3.5 per cent of filicic acid.
TAPEWORM CYSTS OF LIVER AND OTHER VISCERA.
Three kinds of tapeworm cysts are found in the viscera of cattle. One of these (Multiceps multiceps, or Cœnurus cerebralis) will be further referred to in the discussion of gid ([p. 528]). All these are the intermediate stages of tapeworms, which live when mature in the intestines of dogs, wolves, and other canines. The eggs of the tapeworms are scattered over the fields in the droppings of infested dogs or wolves, and when swallowed in food or water by cattle hatch out and the embryos migrate to the liver, mesentery, lungs, brain, or other organs, where they develop into cysts, variously known as hydatids, bladder worms, water balls, etc. When organs of cattle thus infested are eaten by dogs or wolves the cystic worms are also liable to be swallowed and then develop into mature tapeworms. To prevent cattle from infection with these parasites stray dogs, wolves, and coyotes should be killed wherever found, and dogs too valuable to kill should be kept free from tapeworms. As a precaution against infection with tapeworms, the viscera of cattle, sheep, or hogs should not be fed to dogs unless cooked.
Fig. 22.—Hydatids (Echinococcus granulosus) in portion of hog's liver.
Hydatids (Echinococcus granulosus) form tumors (fig. 22) of varying size (sometimes as large as 6 inches in diameter) in the liver, lungs, and other organs. Their contents are liquid, resembling water. The presence of these parasites can not be detected in the living animal and there is no medicinal treatment for them. Organs containing hydatids should be destroyed by burning in order to prevent their being eaten by dogs. This is especially important, as dogs infested with the tapeworm stage of this parasite are a menace to human beings on account of the danger of infecting them with hydatids, which develop in man if the eggs of the hydatid tapeworm are swallowed.
Thin-necked bladder worms (Tænia hydatigena, fig. 23) are most commonly found attached to the mesentery and omentum. There is no medicinal treatment.
Gid.—Bladder worms (Multiceps multiceps, or Cœnurus cerebralis), which are occasionally found in the brain of cattle and cause gid, "turnsick," or "staggers," deserve mention, as they are rather common among sheep in the Northwest. As already alluded to, these worms are the intermediate stage of a tapeworm found in dogs, and their life history and the means of preventing infection have been briefly discussed above (see p. 527).
Cattle harboring this parasite show symptoms indicating an affection of the brain, walking or turning in circles, dizziness, uneven gait, impaired vision, etc.
Treatment consists in trephining the skull and removing the parasite, an operation which requires a skillful operator and is frequently unsuccessful. Unless the parasite is removed affected cattle almost invariably die.
TAPEWORM CYSTS IN THE MUSCLES, BEEF MEASLES.[19]
Fig. 23.—Thin-necked bladder worm (Tænia hydatigena) from abdominal cavity of a steer.
Small tapeworm cysts (Tænia saginatæ), about the size of a pea, found in the muscles of cattle are the larvæ of the common tapeworm of man. Cattle become infected from feed or water which has been contaminated by the feces of persons harboring the adult tapeworms, and human beings in turn become infected by eating raw or rare beef infested with the larval stage (measly beef).
To prevent cattle from becoming infested with this parasite care should be taken that human feces are not placed where they will contaminate the feed or drinking water.
This parasite is very common in cattle in the United States, at least 1 per cent being infested. As a result considerable loss is entailed through condemnations of beef carcasses by meat inspectors, because of the presence of tapeworm cysts. All this loss could be avoided and the danger of tapeworm infestation in human beings from this source could be removed by the observance of proper precautions in disposing of human excreta. At the same time much sickness and many deaths from diseases (hookworm, typhoid fever, etc.) caused by soil pollution would be prevented, and farm life would be rendered much safer than under the poor sanitary conditions which are responsible for the high percentage of tapeworm cysts among cattle in the United States.
THREAD WORMS IN THE ABDOMINAL CAVITY.
Thread worms (Setaria labiato-papillosa) 2 to 4 inches long are frequently found in the abdominal cavity. They seem to cause little or no trouble. The embryos produced by these worms enter the blood vessels. According to Noé, they are spread from one animal to another by stable flies (see [p. 503]), but this has not been definitely proved. The roundworms found occasionally in the anterior chamber of the eye (see [p. 531]) are perhaps immature forms of this species which have reached this location during their migration.
LUNG WORMS.
Lung worms (Dictyocaulus viviparus, fig. 24) in cattle are thread-like worms 2 to 4 inches long, found in the bronchial tubes and producing a condition known as verminous bronchitis. The life history of the parasite is not fully known, but infection is evidently derived through the medium of pastures where infested cattle have grazed. In the later stages of the disease the cattle cough, especially at night. Young cattle are more seriously affected than old animals.
Treatment for lung worms.—Various treatments have been advocated
Fig. 24.—Lung worm (Dictyocaulus viviparus) of cattle. Outlines showing natural size of male (above) and female.
for lung worms, including fumigating with different substances and injections of remedies into the trachea by means of a large hypodermic syringe or by a special spraying apparatus, but none have been very successful from a practical standpoint. About all that can be done is to feed affected animals well and protect them from exposure, removing them from the pasture and keeping them in dry yards or stables maintained in a cleanly, sanitary condition.
The methods of prevention in general are similar to those described under the discussion of the twisted stomach worm ([p. 521]).
PARASITES OF THE BLOOD.
Certain flukes (Schistosoma bovis and related species) which live in the blood vessels (the large veins) of cattle in tropical and sub-tropical countries cause bloody urine and diarrhea, the feces being mixed with blood. These parasites have not yet been discovered in the United States, although the natural conditions are such in some parts of the country that they are liable to become established if introduced.
The embryos of Setaria labiato-papillosa ([p. 529]) which occur in the blood may be found by microscopical examination. They apparently cause no trouble.
The organism which causes Texas fever is a protozoan parasite (Piroplasma bigeminum) of microscopic size, which lives in the blood and attacks the red blood corpuscles. For a discussion of this parasite and the disease which it produces see [page 476] of this volume.
Other parasites which live in the blood cause serious diseases known as surra and nagana ([p. 500]), but as yet neither of these diseases has gained a foothold in the United States.
PARASITES OF THE EYE.
Small roundworms, one-third to four-fifths of an inch in length, may occur in the ducts of the lacrimal glands. Several species all belonging to the same genus (Thelazia) are known. They sometimes escape from their usual location and may be found on the surface of the eyeball beneath the lids, or even in the eyeball. It has been supposed by some writers that the worms seen in the interior of the eyeball ("snakes in the eye") are immature stages of Setaria labiato-papillosa (see [p. 529]) which have gone astray from the normal course of their migration, but the correctness of this supposition is uncertain.
Worms in the eyes and lacrimal ducts may cause inflammation, in which case the eyes may be syringed with an antiseptic, such as a weak solution of coal-tar stock dip, and iodoform ointment applied if the condition is severe.
When worms are present in the eyeball itself, their removal depends upon surgical treatment, usually not advisable, as the worms in that location either cause but little trouble or disappear without treatment.