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.

[Ill.u.s.tration: 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 quant.i.ty. 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 quant.i.ty 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 pa.s.s 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 s.e.xes 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 larvae 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 pa.s.sages 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 debris 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.

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.

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 gra.s.s-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.

[Ill.u.s.tration: FIG. 12.--Portion of the wall of the first stomach with conical flukes attached.]

THE TWISTED STOMACH WORM (HaeMONCHUS CONTORTUS).

The twisted stomach worm (_Haemonchus 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 appet.i.te, 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 1/2 inch to 1-1/4 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.

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 mult.i.tude of eggs (fig. 14_c_) of microscopic size, which pa.s.s 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 larvae 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 larvae 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 larvae are then ready to be taken into the body. The eggs and early stages of the larvae apparently do not develop if swallowed, and only the completed larval stage seems to be infectious. In this stage the larvae migrate up gra.s.s 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 gra.s.s the young worms cease their activity, resuming their migrations when the air again becomes overladen with moisture. Larvae 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.

_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 gra.s.s and on the ground, and this means of disinfection under certain circ.u.mstances 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 bra.s.s 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 a.s.sistant 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.