Chapter 59

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 principal 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.

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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.

Fig. 3. Appearance of the urine in an acute, fatal case of Texas fever.

Fig. 4. Red corpuscles, magnified 1,000 diameters, containing the parasite of Texas fever. This appears as a blue point _a_ near the edge of the corpuscle. The blood was taken from a skin incision. The case was nonfatal and occurred late in the fall.

Fig. 5. Red corpuscles from the blood of an acute, fatal case, 20 hours before death. The Texas-fever microbes _a_ are shown as pear-shaped bodies, stained with methylene blue, within the red corpuscles. The larger body on the right _b_ is a white blood corpuscle, also stained with methylene blue. (Magnified 1,000 diameters.)

PLATE XLVI. The cattle tick (_Margaropus annulatus_), the carrier of Texas fever.

Fig. 1. A series of ticks, natural size, from the smallest, just hatched from the egg, to the mature female, ready to drop off and lay eggs.

Fig. 2. Eggs, magnified 5 times.

Fig. 3. The young tick just hatched (magnified 40 times).

Fig. 4. The male after the last molt (magnified 10 times).

Fig. 5. The female after the last molt (magnified 10 times).

Fig. 6. A portion of the skin of the udder, showing the small ticks. From a fatal case of Texas fever produced by placing young ticks on the animal. (Natural size.)

Fig. 7. A portion of the ear of the same animal, showing same full-grown ticks ready to drop off. (Natural size.)

PLATE XLVII. The cattle tick (_Margaropus annulatus_).

Fig. 1. Dorsal view of male. (Greatly enlarged. Original.)

Fig. 2. Ventral view of male. (Greatly enlarged. Original.)

Fig. 3. Dorsal view of replete female. (Greatly enlarged. Original.)

Fig. 4. Ventral view of same.

PLATE XLVIII. Portion of a steer's hide, showing the Texas-fever tick (_Margaropus annulatus_). (Natural size. Original.)

PLATE XLIX. Fig. 1. Tick-infested steer.

Fig. 2. Dipping cattle to kill ticks.

PLATE L. Facsimile of poster used to show the difference between cattle of similar breeding raised on a tick-free farm in one case and on a ticky farm in the other.

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CHRONIC BACTERIAL DYSENTERY.

Chronic bacterial dysentery is a chronic infectious disease of bovines caused by an acid-fast bacillus simulating the tubercle bacillus and characterized by marked diarrhea, anemia, and emaciation, terminating in death.

This disease was observed in the United States for the first time by Pearson in Pennsylvania cattle, and later by Mohler in Virginia cattle, and in an imported heifer from the island of Jersey at the Athenia quarantine station of the Bureau of Animal Industry.

Pearson proposed the name chronic bacterial dysentery for this affection, and it has also been termed Johne's disease, chronic bacterial enteritis, chronic hypertrophic enteritis, and chronic bovine pseudotuberculous enteritis by various European investigators. The disease was first studied in 1895 by Johne and Frothingham in Dresden, but they were inclined to attribute to the avian tubercle bacillus the cause of the peculiar lesions of enteritis which they observed. In 1904 Markus reported this disease in Holland, and subsequently it was observed in Belgium, Switzerland, Denmark, and Great Britain.

_Cause._--The bacillus, which has been invariably demonstrated in the intestinal lesions and mesenteric lymph glands in this disease, is a rod about 2 to 3 microns long and 0.5 micron wide. It stains more or less irregularly, like the tubercle bacillus, and moreover the similarity goes further, in that the organism is also strongly acid-fast, which facts led Johne and Frothingham to surmise that the disease was caused by avian tubercle bacilli. However, it has now been plainly demonstrated that the bacillus of chronic bacterial dysentery is readily distinguished from the latter organisms, for while it resembles the tubercle bacillus in form and staining qualities, no one has succeeded in growing it in culture media or in reproducing the disease by injecting experiment animals.

_Symptoms._--Probably the first symptom noticed is that the animal is losing condition despite the fact that its appetite is good and the food nourishing. This is soon followed by a diarrhea which, while moderate at first, soon becomes excessive and may be either irregular or persistent, the feces being of the consistency of molasses and passed frequently. In the meantime the hair becomes dry and harsh and the animal falls off considerably in weight. The temperature, however, remains about normal. The appetite does not seem to be greatly impaired until the last few weeks of life, but nevertheless emaciation continues, the animal becomes more and more anemic, great muscular weakness and exhaustion are manifested, and death follows, apparently as the result of the persistent diarrhea and great emaciation. The disease may continue for four or five weeks or may last for a year, or even longer, before death intervenes.

_Lesions._--The lesions observed on post-mortem are remarkably slight and are out of all proportion to the severity of the symptoms manifested. The disease appears to start in the small intestines, especially in the lower portion, where the lesions are usually the most marked, but it also involves the large intestines, including the rectum. The mucous membrane may alone be affected, although usually in the long-standing cases the submucosa is also invaded and the entire intestinal wall is then much thicker than normal and the tissue infiltrated with an inflammatory exudate. The mucous membrane or inside lining membrane is markedly wrinkled or corrugated, showing large, coarse folds with more or less reddening or hemorrhagic patches or spots on the summits of the ridges, especially noticeable in the large intestines. The mesenteric lymph glands are usually somewhat enlarged and appear watery on section. The other organs do not appear to be affected except from the anemia present in the later stages of the disease.

_Differential diagnosis._--The principal disease with which bacterial dysentery may be confused is tuberculosis, but the application of the tuberculin test will readily diagnose the latter disease, while no reaction will be noted in case the injected animal is suffering with the former affection. The disease may also be mistaken for the parasitic affections resulting from stomach worms (verminous gastritis) and intestinal parasites, especially uncinariasis, but a microscopic examination of the feces is necessary in order to establish definitely the diagnosis.

_Treatment._--As with all other forms of infectious disease, it is advisable to separate immediately the diseased and suspected cattle from the healthy animals. The feces passed by the former animals should be placed on cultivated soil where healthy cattle will not be exposed to them, as the bacilli producing the disease are readily found in such manure. The stalls, stables, and barnyards should also be thoroughly disinfected, as has been described under "Tuberculosis," in this chapter, special attention being given to those places which have been soiled by feces. The administration of medicines has thus far been quite unsatisfactory, although treatment should be directed toward disinfecting the intestines with intestinal antiseptics, such as tannopin in 1 dram doses twice daily, and strengthening the animal by the use of stimulants such as strychnin in half-grain doses given twice daily hypodermically. Salol, turpentine, or subnitrate of bismuth in a starch or wheat-flour gruel may also give temporary relief, but the diarrhea is likely to reappear and cause the death of the animal. In all cases the feed must be carefully selected to assure good quality, and should consist preferably of nutritious dry feed.

NAGANA.

Nagana, also called tsetse-fly disease, is an infectious fever occurring chiefly in horses and cattle, characterized by alternating paroxysms and intermissions and produced by a specific flagellate protozoan (_Trypanosoma brucei_) in the blood. It is probably transmitted from animal to animal solely by the bites of the tsetse fly. This insect is something like a large house fly, and when it settles on a diseased animal, sucks the blood and infects its proboscis, it is enabled on biting a second animal to infect the latter by direct inoculation. This disease is found throughout a large portion of central and southern Africa, along the low-lying and swampy valleys. It has never occurred in the United States, nor is it known to be present in the Philippines, but its relation to surra and the possibility of its appearance in one of our island dependencies are the reasons for including a few remarks at this time.

_Symptoms._--The chief symptoms in addition to the fever, which is usually about 104∞ to 105∞ F., are the muscular wasting, progressive anemia, and loss of power, together with the edema most marked about the head, legs, abdomen, and genital organs. The urine is yellow and turbid, and occasionally contains albumin and blood. There is paralysis of one or both of the hind legs, difficult urination and defecation, labored breathing, discharge from the eyes and nose, extreme thirst, and gradual extension of paralysis to other parts of the body. The disease runs a chronic course, lasting from three to six weeks in horses, and from one to six months in cattle. Besides these animals, the mule, ass, buffalo, antelope, hyena, camel, and dog contract the disease naturally, and sheep, goats, cats, and small laboratory animals succumb to artificial inoculation.

_Lesions._--The spleen and lymphatic glands are enlarged. There are sero-fibrinous exudates in the body cavities, the liver is enlarged and engorged, heart flabby, and a catarrhal condition is present in the respiratory passages. Pathological changes occur in the spinal cord. The finding of the trypanosoma by microscopic examination of the blood will be conclusive evidence for diagnosis.

_Treatment._--Treatment has not proved satisfactory. Quinin, arsenic, methylene blue, and other drugs have been used, but without success. Endeavors thus far made to produce immunity from this disease have likewise been unavailing.

CATTLE FARCY.

This is a chronic disease of cattle occurring in France and the island of Guadeloupe, West Indies. It is characterized by caseating nodular swellings, first of the skin and afterwards of the superficial lymphatic vessels and glands, finally proving fatal within a year by extension to the viscera. The swellings rupture and discharge a purulent yellowish fluid, which contains the causative organism. This affection, called farcin du boeuf by the French, resembles cutaneous glanders or farcy of horses, but is caused by an entirely different organism, the streptothrix of Nocard. Moreover, cattle are immune from glanders, and for this reason the name, unfortunately applied to this disease, should not lead to any confusion with the cutaneous glanders or farcy of horses. Although the disease has been described as occurring only in Guadeloupe and France, the possibility of its occurrence in American possessions warrants its mention in this chapter.

_Treatment._--Treatment consists in making incisions into the swellings and syringing them out with 2 per cent compound cresol solution. The cavities may then be packed with cotton, soaked in 5 per cent zinc-chlorid solution. The swollen lymphatics may also be bathed or covered with cloths wrung out in this solution.

OTHER INFECTIOUS DISEASES.

The following are also infectious diseases of cattle, a discussion of which will be found in previous chapters: Page. Contagious abortion 167 White scour of calves 261 Infectious ophthalmia (pink eye) 345

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 NoÈ, it is the agent of transmission of a parasitic roundworm of cattle (_Setaria labiato-papillosa_, see p. 529). This fly has been shown capable of transmitting anthrax from diseased to healthy animals, and under some conditions it may transmit surra, a disease caused by a blood parasite which affects horses, cattle, and other livestock.

The annoyance suffered by cattle and horses from stable flies is much lessened if the stables are darkened.

The screening of doors and windows, however, is preferable, as ventilation is not interfered with as it is in darkening stables. For milk cows coverings made from burlap (double thickness), including trouserlike coverings for the legs, may be used when the flies are very numerous and troublesome. One of the fly repellents mentioned above may be applied to cattle to protect them from stable flies. The Hodge flytrap fitted to the windows of dairy barns is a useful means of destroying stable flies. The United States Bureau of Entomology has found that a mixture of fish oil (1 gallon), oil of pine tar (2 ounces), oil of pennyroyal (2 ounces), and kerosene (1/2 pint) is fairly effective for a short time when applied lightly, but thoroughly, to the portions of animals not covered with blankets. The risk of poisoning with tar mixtures as already mentioned should be borne in mind in using this remedy. Care should be taken to apply it lightly.

The stable fly breeds in moist accumulations of straw, chaff, cow or horse manure, and various fermenting vegetable substances. The dÈbris collecting in and under outdoor feed troughs, and the remains of straw stacks are favorable breeding places for the stable fly. Under the most favorable conditions about three weeks are required for development from the egg to the adult stage.

The proper care of straw and the proper disposal of stable manure are very necessary in the control of stable flies. Straw stacks should be carefully built so as to shed rain, and loose straw or chaff should be scattered or burned. Straw not required for winter feed should be promptly disposed of by burning or scattering and plowing it under. Stable manure should be hauled out and scattered at regular intervals, preferably every three days, and the vicinity of stables should be kept free from accumulations of straw and hay that may become wet and serve as breeding places for the stable fly.

THE HORNFLY (LYPEROSIA IRRITANS).[14]

This fly, now found nearly everywhere in the United States, was introduced into this country from Europe about the year 1885. Hornflies have the habit of clustering about the base of the horn (fig. 2), whence the name by which they are popularly known. They do not damage the horn, and congregate there only to rest.

In view of the general practice of dehorning cattle, the name hornfly is less distinctive than it once was. Moreover, hornflies rest on other parts of the body as well as the horns.