_Diluting the dip._--First run water into the vat about three-fourths up to the dipping line, at which its capacity must be known. If tar stock is to be used the necessary amount will be one-third of a gallon for every 100 gallons of vat capacity. Measure it out, mix it with 2 or 3 times its volume of water and pour it along the surface of the water in the vat, stirring a little.
Every 100 gallons of standard-strength bath calls for 1-3/5 pounds white a.r.s.enic, which quant.i.ty is contained in four-fifths of a gallon of S-B stock or in 5 gallons of boiled stock. From these figures the quant.i.ty of a.r.s.enic or stock needed to charge the vat may be calculated. Or one may base the calculation on the following facts:
One pound of white a.r.s.enic will make 62-1/2 gallons of bath.
One gallon of S-B stock will make 125 gallons of bath.
One gallon of boiled a.r.s.enic stock will make 20 gallons of bath.
All solutions of a.r.s.enic are considerably heavier than water and if carelessly put into the vat they may plunge to the bottom and be difficult to mix. Therefore always pour the a.r.s.enic stock or a proprietary dip in a thin stream evenly along the vat except at the shallow exit end. Another precaution to be taken in handling proprietary dips is never to mix them first with small quant.i.ties of water, which may "break" them. Pour them directly into the water in the vat.
Finally, add water up to the dipping line and stir well. An excellent way to stir is by a pail tied to a rope. Sink it at the entrance end of the vat and haul it along the bottom to the exit. Then raise it, throw it back to the entrance end, and haul through again, repeating as many times as necessary but always hauling through in the same direction.
The standard-strength bath prepared as above contains practically 0.19 per cent a.r.s.enious oxid when fresh. After use oxidation may set in and weaken it, but it will not need to be strengthened so long as it tests not less than 0.175 per cent a.r.s.enious oxid.
To make up small quant.i.ties for spraying, to each 5 gallons of water measured out add first 2 fluid ounces (4 tablespoonfuls) of tar stock, and then 5-1/8 fluid ounces of S-B stock or 2-1/8 pints of boiled a.r.s.enic stock.
The standard strength of bath should be adhered to so far as possible because its effectiveness against ticks will effect eradication in the least time and with fewest dippings. But if time is not pressing it is sometimes best to begin with a lower strength, say 0.14 or 0.15 per cent, and gradually work up to full strength as the cattle become accustomed to the treatment. This is certainly a wise method for the individual cattle owner who is outside the area of cooperative work and who lacks aid and advice from experts. Weather conditions also need to be considered. Hot or moist weather is more trying to the cattle than cool or dry weather. The longer the time needed for the cattle to dry off after dipping, which of course primarily depends on the proportion of moisture in the air, the more liable they are to show blistering or other injury through the continued absorption of a.r.s.enic by the skin. The combination of heat and moisture is particularly bad, and under such conditions it may be desirable, unless other conditions prohibit, to use the bath somewhat weaker than standard strength. The following table shows the quant.i.ties of a.r.s.enic and stock solutions contained in 100 gallons of bath of different strengths, so that the quant.i.ties necessary to charge a vat of any size at any strength can be found by simple multiplication.
_Composition of dipping baths._
+-----------+------------------------------+ | Actual | Per 100 gallons of bath. | | a.r.s.enious +------------------------------+ | oxid. | White | S-B | Boiled | | | a.r.s.enic. | stock. | stock. | +-----------+----------+---------+---------+ | Per cent. | Pounds. | Gallons.| Gallons.| | 0.05 | 0.42 | 0.21 | 1.3 | | .06 | .50 | .25 | 1.6 | | .07 | .58 | .29 | 1.8 | | .08 | .66 | .33 | 2.1 | | .09 | .75 | .38 | 2.3 | | .10 | .83 | .42 | 2.6 | | .11 | .91 | .46 | 2.8 | | .12 | 1.00 | .50 | 3.1 | | .13 | 1.08 | .54 | 3.4 | | .14 | 1.16 | .58 | 3.6 | | .15 | 1.25 | .63 | 3.9 | | .16 | 1.33 | .67 | 4.2 | | .17 | 1.41 | .71 | 4.4 | | .18 | 1.49 | .75 | 4.7 | | .19 | 1.58 | .79 | 4.9 | | .20 | 1.66 | .83 | ... | | .21 | 1.74 | .87 | ... | | .22 | 1.83 | .92 | ... | | .23 | 1.91 | .96 | ... | | .24 | 2.00 | 1.00 | ... | +-----------+----------+---------+---------+
As dipping goes on the bath naturally needs replenishing, and its strength probably needs correction from time to time. Full directions on these points may be found in Farmers" Bulletin 1057.
_Prepared dips._--Proprietary a.r.s.enical cattle dips appear now to have pa.s.sed the experimental stage and to have become established as reliable and useful products. At any rate this can be said of the brands which have received permission for use in official dipping in place of the homemade dip. The formulas and standard samples of all such brands are in possession of the Bureau of Animal Industry and the manufacturers are required to guarantee that their products as placed on the market will be kept up to standard and that all requirements of the bureau will be observed. Like the homemade dip they all contain sodium a.r.s.enite as the active tick-killing agent. They do not all contain pine tar, because that substance is difficult to blend into a highly concentrated product, but they all contain some other substance or mixture of substances of such character and in such quant.i.ty as field trials have proved will produce the same effects.
They are not regarded as any more effective or any milder on the cattle than properly prepared homemade dips. None the less they are undoubtedly safer for general use because they offer decidedly fewer opportunities for making mistakes in the quant.i.ties used or in the operations gone through and also fewer chances for accidental poisoning or other injury from the handling of powerful chemicals. Whether their higher cost is sufficiently outweighed by these considerations is necessarily a matter for individual decision.
_Precautions in the use of a.r.s.enic and a.r.s.enical dips._--The fact that a.r.s.enic is a violent poison is what renders it valuable, for the fever tick is hard to kill. But, like a keen-edged tool, it may be decidedly dangerous if ignorantly or carelessly handled. Three possibilities of danger must be kept constantly in mind; danger to oneself, danger to other persons, danger to animals.
The dry, powdered white a.r.s.enic should be kept in a tightly covered pail, plainly labeled. Paper bags are unsafe because they easily burst, and a.r.s.enic so scattered about looks harmless enough. In weighing or otherwise handling the a.r.s.enic avoid raising dust or breathing it in, if raised, and keep it off the skin and clothing. In mixing or boiling stock solutions work only in a well-ventilated place, and on the windward side of the kettle so that steam arising from it will not be inhaled.
The stock solutions are in some respects more dangerous than the original substance because the a.r.s.enic in them is already in solution and can act very quickly. If any gets on the skin or clothing it must be washed off without delay. Cattle must be kept away from such solutions or from anything that has been in contact with them, for cattle craving salt have been poisoned by licking the outside of leaky barrels and by licking the earth around dipping vats where a little concentrate had been carelessly spilled in charging the vat. All such poisoned earth must be removed, buried, and replaced by fresh.
The diluted bath is naturally much less dangerous, but no chances can be taken with it. No puddles from which animals may drink should be allowed to acc.u.mulate. The persons who do the dipping should not allow the skin or clothing to be wet by the dip any more or any longer than absolutely necessary. When spraying, the operator should see to it that neither he nor the animals inhale any of the spray.
When a vat is to be emptied the approved practice is to run the waste bath into a pit properly guarded by a fence, where it will gradually seep away under the surface and do no harm, provided only that seepage can not be carried to a well, stream, or spring from which any person or domestic animal may drink.
The symptoms of a.r.s.enical poisoning are rather variable and also depend on the size of the dose and the method of administration. If an animal sickens or dies shortly after dipping it by no means follows that a.r.s.enical poisoning or any other effect of the dipping is the cause. Very few cattle relative to the total number dipped have suffered undoubted a.r.s.enical poisoning and in most of the cases the cause could be traced to somebody"s error or carelessness.
In regard to a.r.s.enical poisoning of human beings there is a standard antidote, which may be obtained at any drug store with directions for use.
It should be kept on hand for emergencies. If the antidote is not at hand the poison must be removed from the stomach by encouraging repeated vomiting, and soothing drinks such as milk, white of eggs and water, or flour and water must be freely given meanwhile. A suspected case of a.r.s.enical poisoning must have the attention of a physician at the earliest possible moment, as sometimes the poison works very quickly.
_Crude petroleum._--Various kinds of crude petroleum and emulsions of it have been used with more or less success in destroying ticks, but on account of the difficulty of obtaining suitable grades of oil and the liability of injury to cattle, their use has been practically abandoned.
_Method of dipping._--The method usually adopted in dipping cattle is to construct a narrow swimming tank with a chute at one end for the entrance of the cattle, and a sloping exit at the other end when the cattle emerge after pa.s.sing through the vat. (See Pl. XLIX, fig. 2.) A drip chute, or floor, is connected with the exit, where the excess of dip is allowed to drip off the animals and to drain into the vat. Plans and specifications for installing dipping plants may be obtained from the Bureau of Animal Industry, Department of Agriculture, Washington, D. C.
TREATMENT.
When Texas fever has broken out, all animals, the sick as well as the healthy, should at once be removed to a noninfected pasture. While this may not cut short the disease, it may save the lives of some by removing them from the possibility of attack by more young ticks. Removal from infected pastures likewise prevents a second attack, in October or early in November, which is caused by another generation of ticks. Sick native cattle infect with a new generation of ticks the pasture to which they are removed, but these usually appear so late that they have but little opportunity to do any damage; hence, sick natives do not, as a rule, cause visible disease in other natives.
It is of importance to remove all ticks, so far as this is possible, from sick animals, since they abstract a considerable quant.i.ty of blood and thereby r.e.t.a.r.d the final recovery.
Medical treatment of the sick has generally been unsatisfactory, although in chronic cases and those occurring late in the fall beneficial results have followed. If the animal is constipated, a drench containing 1 pound of Epsom salt dissolved in 1 quart of water should be administered, followed by sulphate of quinin in doses of 30 to 90 grains, according to the size of the animal, four times a day until the system is well saturated with it.
Tincture of digitalis one-half ounce and alcohol 2 ounces may be combined with the quinin, according to indications of individual cases. An iron tonic containing reduced iron 2 ounces, powdered gentian 4 ounces, powdered nux vomica 2 ounces, powdered rhubarb 2 ounces, and pota.s.sium nitrate 6 ounces will be found beneficial in the convalescent stage when the fever has run its course. This tonic should be given in heaping teaspoonful doses three times a day in the feed. Good nursing is essential in treating these cases, and the animal should be given a nutritious, laxative diet with plenty of clean and cool drinking water and allowed to rest in a quiet place. If the stable or pasture is infested with ticks, the animal should be placed in a tick-free inclosure to prevent additional infestation with these parasites and the introduction of fresh infection into the blood.
Furthermore, all ticks that can be seen should be removed from the sick cattle, as they keep weakening the animal by withdrawing a considerable quant.i.ty of blood, and thereby r.e.t.a.r.d recovery.
QUARANTINE REGULATIONS.
The sanitary regulations issued by the Department of Agriculture for the control of cattle shipments from the infected districts have for their initial purpose the prevention of the transportation of ticks from infected regions to those that are not infected, either upon cattle or in stock cars or other conveyer. They are based upon the fact that Texas fever is carried north only by the cattle tick, and the exclusion of this parasite from the noninfected territory has in every instance been found a certain method of excluding Texas fever. The regulations governing the movement of cattle from below the quarantine line are made yearly by the Secretary of Agriculture, and they define the boundary of infected districts. The infected area as now determined is shown in maps issued periodically.
In consequence of the enforcement of these quarantine regulations, Texas fever has been practically prevented in the noninfected districts for several years, and little or no hardship has been caused to stockmen handling cattle from the infected areas. Prior to the adoption of these regulations the tick-infested district was rapidly extending northward, but since the quarantine line was established and rational regulations enforced it has gradually been moved farther south. This problem of still further reducing the infested area is of the greatest importance to the cattlemen of the South--in fact, to those on both sides of the line--and one which is receiving special consideration by this department as well as by many of the interested States.
TICK ERADICATION.
Systematic cooperative work by the Federal Government and the affected States for the eradication of the cattle ticks which transmit Texas fever was begun in the summer of 1906 under authority given by Congress in the appropriation act for the Department of Agriculture. The first Federal appropriation for the fiscal year ended June 30, 1907, was $82,500, and for the fiscal year 1908 an appropriation of $150,000 was made, then for several years $250,000, and this has been increased to $660,000 for 1922.
Funds have also been provided by States and counties.
The original infected area amounted to 728,543 square miles. Of this territory there has been released from quarantine as a result of the work above mentioned 523,837 square miles (up to July 1, 1922). In other words, 72 per cent of the area has been freed from ticks in 16 years.
Great improvement has resulted from this work in the released territory.
More cattle are being raised, and a better grade of breeding stock is being introduced; calves grow faster, and cattle put on flesh more rapidly during the grazing season and go into the winter in better condition because of the absence of the ticks; they can be marketed without quarantine restrictions, and higher prices are being obtained; dairy cows give a larger yield of milk; and values of farm lands are enhanced.
The difference between the prices realized for cattle from the tick-infested region and the prices of cattle of similar grades from above the quarantine line has ranged from $2.25 to $5 a head at the princ.i.p.al northern live-stock markets, without taking into account the improvement in quality and weight of cattle because of the eradication of the ticks. It can easily be seen that the extermination of the ticks means a large total annual increase in the prices obtained for southern cattle sold in northern markets. In addition to this, the increase in prices of cattle sold locally in the South would represent a large sum. This local increase has been found to amount to from $3 to $15 a head in territory freed from ticks. An agricultural official of one of the Southern States has reported that calves in the tick-free area bring double the prices that can be obtained for similar calves in the tick-infested region.
Heretofore it has been impracticable to improve the quality of southern cattle by introducing fine breeding animals from other sections, because such animals were liable to contract Texas fever and die unless protected by inoculation. Furthermore, it is impossible for animals to attain good growth and to thrive when they are heavily infested with ticks. With the eradication of the ticks, however, the southern farmers are enabled to introduce good breeding animals and to improve the grade of their stock.
There is no longer any doubt that it is entirely practicable to exterminate the ticks throughout the entire region, and the accomplishment of this result will be of tremendous economic advantage not only to the South but to the whole country. The rate of progress depends mainly on two factors-- the amounts appropriated by the Federal and State Governments, and the cooperation of the people.
SOUTHERN CATTLE FEVER (TEXAS FEVER, TICK FEVER).
DESCRIPTION OF PLATES.
PLATE XLIV. Normal spleen and spleen affected by Texas fever.
Fig. 1. Spleen of an acute, fatal case of Texas fever. The narrow end of the spleen is here represented.
Fig. 2. Spleen of healthy steer. Though the latter animal weighed one-half more than the former, the weight of the diseased spleen (6-7/8 pounds) was nearly three times that of the healthy spleen (2-3/8 pounds).
PLATE XLV. Texas fever.
Fig. 1. The cut surface of a healthy liver taken from a steer slaughtered for beef.
Fig. 2. The cut surface of the liver in Texas fever.