SPECIAL REPORT ON DISEASES OF CATTLE TEXT

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 larvÊ, 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. [Illustration: 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).] LICE.[16] Cattle in the United States are commonly infested with three species of lice, two of them sucking lice (_HÊmatopinus 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. 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. 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, 1/2 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. 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. 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. [Illustration: FIG. 7.--Short-nosed blue louse (_HÊmatopinus eurysternus_) of cattle. Enlarged. (From Bureau of Entomology.)] [Illustration: FIG. 8.--Long-nosed bluelouse (_Linognathus vituli_) of cattle. Enlarged. (From Bureau of Entomology.)] [Illustration: FIG. 9.--Red louse (_Trichodectes scalaris_) of cattle. Enlarged. (From Bureau of Entomology.)] [Illustration: FIG. 10.--Egg of short-nosed blue louse (_HÊmatopinus eurysternus_) attached to a hair. Enlarged. (From Bureau of Entomology.)] MANGE, ITCH, SCAB.[17] Cattle are subject to four kinds of mange, of which common mange or psoroptic mange is the most important. 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 1-1/2 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. [Illustration: FIG. 11.--Mite which causes psoroptic scab of sheep. Enlarged about 100 times. The mite of psoroptic cattle mange is almost identical in appearance.] 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