UNIVERSITY OF CALIFORNIA Agricultural Experiment Station COLLEGE OF AGRICULTURE E, W. HILGARD, DIRECTOR BERKELEY, CALIFORNIA CIRCULAR No. 1 (May, 1903.) TEXAS FEVER By ARCHIBALD R. WARD, Veterinarian and Bacteriologist. Synonyms.— Other names by which the disease is known are: South- ern Cattle Fever, Bloody Murrain, Splenic Fever, Red Water, Tick Fever, etc. Symptoms. — In the acute (severe) type of the disease a fever is noticed, and results in dullness, lack of appetite, and constipation. The pulse and respiration both increase in rapidity. The muzzle and mouth may be dry and the head usually droops. Affected animals prefer to stand in water. Some animals exhibit extreme dullness, but others may be delirious and unusually active. The one most characteristic symptom is the voiding of dark, blood-colored urine by animals in the advanced stages of the disease. When any considerable number of animals are affected, some of them are quite sure to exhibit this symptom, which is of great value in recognizing Texas fever to those unfamiliar with it. During the progress of the disease the victims grow steadily weaker, appearing pale and bloodless. The attack may run a week, and result in death or slow recovery, frequently with relapse. Deaths frequently occur within a few days after the animal is noticed to be ailing. In some animals, not very susceptible to the disease, it assumes a mild type, manifested by dullness, lack of appetite, and costiveness. Texas fever is exclusively a cattle disease and is active during hot weather. Post-mortem Appearances. — The liver and spleen (milt) are the organs most usually altered in appearance. The liver is enlarged, and the organ is not as tough as in health. The color is usually brownish yel- low, due to bile dammed up in the biliary vessels. The gall bladder is distended with thick, tarry bile. The spleen is enlarged, and if cut open the contents will flow out slowly like thin jam. The blood is noticeably thin and pale. There occur other changes not readily recognized by persons unfamiliar with the study of diseases. % — 2 — Cause of the Disease. — The above-mentioned changes in the body, and others that can be detected only with the microscope, are caused by minute animal parasites in the blood. The red-blood corpuscles are infested with the parasites, which bring about the destruction of the corpuscles and prevent the blood from performing its natural function in the body. The blood-colored urine, in severe cases, is an evidence of the breaking down of these corpuscles, resulting in the discharge, through the urine, of the red coloring matter of the blood, which is normally carried by the corpuscles. The microscopic examination of the blood of an affected animal will reveal the parasites imbedded in the corpuscles, but visible only as small round or pear-shaped dots even with the best microscope. The parasites are always present in the blood of an animal sick with Texas fever, but under certain conditions may be present in limited numbers without causing sickness. How Texas Fever is Spread. — For all practical purposes we may con- sider the disease as being communicated from one animal to another by means of the cattle tick (Boophilus annulatus), and by no other species of tick. The disease is not known to be spread by any other means. The habits and life history of this tick are intricately involved in the spread of the disease and furnish explanation for all of the principal peculiarities observed in the spread of Texas fever. The cattle tick lives a parasitic life, usually in some unexposed place, upon the hide of cattle, sucking the blood. If the blood of the host contains the Texas-fever parasites, as is practically always the case, the ticks become infested with them. When the female ticks reach maturity (one quarter to half an inch long) they loosen their firm hold upon the skin and drop to the ground. Each female may lay from 1,200 to 3,000 eggs, after which she dies. The eggs hatch in about twenty days, but the hatching may be retarded or prevented by unfavorable conditions, chief among which is brilliant sunlight. The young ticks, when not clustered together, are readily killed by water; and a temperature of 15° Fahr. for twenty-four hours will kill them. They are endowed with an instinct to climb upon cattle within a few days after hatching, if opportunity occur; but in the absence of cattle (or horses) they will starve in time. If the female tick has been nourished with blood containing the Texas-fever parasites, all the young ticks hatching from her eggs will contain the Texas-fever parasites. When such a young tick gains access to an animal and sucks blood, the Texas-fever parasites are imparted to the blood of the animal upon which the young tick is living. If the animal infested by the young ticks is susceptible to Texas fever, the disease will appear in about ten days after the ticks get on it. The ticks mate shortly after infesting an animal, and nowhere else; after which they become firmly fixed to their host without leaving the animal until ready to drop off, as already- described. Since cold weather kills ticks, their eggs and young, the species in question is limited to mild climates. During the summer, ticks may be introduced into the northern parts of the United States and occasion immense damage, but the rigorous winter climate exterminates the ticks and consequently the disease. There are several species of ticks that occasionally are found on the hides of cattle or in their ears; but only one kind, popularly known as the "fever tick/' is concerned with the spread of Texas fever. This species practically always contains the Texas-fever infection, unless it has been parasitic upon the horse, which occurs sometimes. The Seventeenth Annual Report of the Bureau of Animal Industry at Washington contains a description of the cattle ticks of the United States, together with colored illustrations. The book can in most cases be obtained from Members of Congress, or by purchase from the Super- intendent of Documents, Union Building, Washington, D. C. The Veterinarian of the Agricultural Experiment Station at Berkeley will be glad to identify specimens of ticks sent him by mail. Why Ticks May Infest Cattle Without Causing Texas Fever. — Among a herd of cattle infested with the Texas-fever ticks the calves become infested with ticks when very young, and suffer a mild attack of Texas fever. Calves withstand the disease readily and seldom die. As a result of this attack they grow up practically immune to the disease, and are usually able to tolerate the presence of numerous ticks upon their bodies. This immunity is not absolute, for animals excessively covered with ticks may again contract the disease under especially unfavorable conditions, with fatal results. The fact that animals may bear ticks without necessarily contracting Texas fever has induced some people to refuse to believe that ticks are dangerous under any conditions. Such a view of the matter is indefensible. Conditions Under Which Ticks Are Dangerous. — All cattle other than young calves are liable to contract a serious type of Texas fever when first bitten by infectious ticks. The disease is therefore a menace to all cattle raised in regions where cattle ticks do not exist. Whenever tick- infested cattle come in contact with non-immune, i. e., tick-free cattle, some of the latter will contract the disease after ten days or more- Worse yet, the disease may be contracted by susceptible animals by feeding upon a range formerly occupied by tick-infested cattle, for young ticks may be present waiting to attach themselves to the cattle. Losses will occur from Texas fever when tick-infested southern cattle are taken north among non-immunes, just as soon as a female tick drops off to __ 4 — the ground and the second generation gets upon the northern cattle. Northern-bred animals will contract the disease when taken among ticks. An animal may be bred in the south in close proximity to ticks and yet escape them until it reaches adult age, when it will suffer from the disease if infested by ticks. The Federal Quarantine Line. — To restrict the movement of cattle from tick-infested regions to tick-free regions, the United States Depart- ment of Agriculture has established a quarantine line across the con- tinent from the southern boundary of Virginia to the Bay of Monterey? in California. In California the Federal quarantine line lies as follows: " Beginning on the Pacific Coast where the northern boundary line of " Monterey County connects with the Pacific Ocean ; thence easterly " and southerly along the northern and eastern boundary line of Mon- " terey County to its junction with the western boundary line of Fresno " County; thence northerly along the western boundary line of Fresno " County to the western corner thereof ; thence northerly, easterly, and " southerly along the western, northern, and eastern boundary line of " Merced County to the southeastern corner thereof ; thence north- " easterly along the northern boundary line of Madera County to the u northeast corner thereof ; thence southerly and easterly along the " eastern boundary lines of Madera, Fresno, and Tulare counties to the " southeast corner of Tulare County ; thence easterly along the southern u boundary line of Inyo County to its intersection with the eastern " boundary line of the State of California." The line marks the southern boundary of the region free from ticks, and is moved from time to time as the ticks are exterminated from pieces of territory contiguous to the line on the south, or as the ticks encroach upon the territory to the north of the line. Under the regu- lations of the United States Department of Agriculture and the laws of California the movement of cattle across the line is restricted so as to minimize the losses from Texas fever. Tick-infested cattle des- tined to a slaughter-house may be taken across the line at any time, but others from certain districts may be transported across the line only when inspected by State or county inspectors and pronounced free from ticks. There are many districts south of the quarantine line in Cali- fornia that are free from ticks, and consequently cattle therein should be and are allowed to be taken north after inspection. For more exact information concerning the regulations affecting the movement of cattle address inquiry to the State Veterinarian, Sacramento, California. Inoculating for Texas Fever. — Moving susceptible animals into tick- infested regions is always attended with risk. Calves taken in during the winter have the best chance to escape. At that time the ticks are not numerous, and the age of the calves and the climatic conditions of — 5 — winter favor their recovery when infested by the ticks. But there are numerous occasions when it would be desirable to move susceptible adult animals on to tick-infested ranges, and in consequence an opera- tion known as inoculation or vaccination has been devised. The process consists in transferring to the susceptible animal some blood from a tick- infested animal, and thereby producing an attack of the disease usually mild and not fatal ; that is, the animal is artificially immunized against Texas fever. The operation is sometimes designated vaccination. It is most safely performed in California during the winter months and at a time when feed is good, as these conditions are conducive to the recovery of the animal from the inoculation attack of the fever. The existing methods of inoculation for Texas fever have hardly been simplified enough to justify recommending their use by men unskilled in the work. Inoculation, unless performed by a man thoroughly familiar with the disease, is liable to lead to disastrous results. The writer believes that he is ministering to the best interests of stockmen in advising the employment of a competent veterinary surgeon to do the work. This so-called vaccination is not a remedy, and should not be practiced upon sick animals. Recognition of Texas Fever. — The disease is not difficult to recognize. Practically always the history of the outbreak shows that there has been the movement of one or more animals in such a way as to result in the infestation of non-immune animals by ticks. One must not expect to succeed in finding the ticks upon a freshly-infested animal, for they are so small as to practically elude discovery. The fact that they could not find ticks on the affected animals has led many stock owners to errone- ously conclude that their cattle were not suffering from Texas fever. Further facts to assist in recognition are fever, gradually increasing weakness, and voiding of red-colored urine. Conclusions may be further strengthened by examining the liver and spleen after death. Hogs are not injured by eating the flesh of cattle dead of Texas fever. Treatment of Texas Fever. — Removal of the animals from the infested range is essential. The removal of the ticks is desirable, but attended with considerable difficulty. With large numbers of range stock this is accomplished with more or less completeness by dipping the animals in a large vat constructed for the purpose and containing some substance harmful to the ticks. A grade of oil known as extra dynamo oil has been used, floating in a layer several inches deep on the vat of water. One per cent of sulfur has been found to improve its action. Fish oil has been used successfully in the same manner in a vat or has been applied to tame cattle by hand, with satisfactory results. Cooper Curtice sug- gests the following mixture : Kerosene and lard, of each, one gallon ; sulfur, one pound, and two pounds of pine tar. Melt the lard, to which — 6 — should be added the tar and sulfur, all of which is brought to the boil- ing point. Cool, and stir in the kerosene. This is to be rubbed over the animal daily. Such treatment is only applicable to small numbers of domesticated animals. Cottonseed oil has been used with success on small numbers of cattle- Practically all of the numerous dips that have been devised are unsatis- factory in some respects. Some injure the health of the animals, especially the eyes; others are inefficient in not killing the ticks with one dipping. Oil dips, on the whole, are the most satisfactory of all the various dips that have been tested for killing ticks. But the operation of dipping, however necessary, sometimes tends to aggravate the disease. Medical treatment is practicable only when it is desired to save some particularly valuable animal. A dose of a pound and a half of Epsom salts, together with an ounce of ginger, should be given in a drench. Dr. J. C. Robert, of the Mississippi Agricultural Experiment Station, advises the following treatment : "Administer bisulfate of quinine in "from 60 to 120 grain doses, dissolved in one half pint of water. Give " the quinine every two to four hours as long as the temperature of the "animal remains above 103° Fahr , then gradually decrease the dose. " Should the animal grow weak, it should have combined with the quinine " from one to three ounces of alcohol or twice that amount of whisky. " When improvement commences the administration of an iron tonic " will be found of value. We may prepare such a tonic by the use of " powdered sulfate of iron 2 parts, powdered nux vomica 1 part, powdered "gentian root 1 part, sulfate of soda 2 parts, and common salt 4 parts ; " mix these ingredients and give to a grown animal from one to one and "one half heaping tablespoonfuls in feed twice daily. Too much pains " can not be taken with nursing a case of Texas fever. The high fever " incident to the disease rapidly exhausts the animal's strength, and "unless the proper nourishment and care is given death may result " before we look for it. Give tempting, nutritious, laxative diet and pure "drinking water. If the animal refuses to eat, drench every four hours " with one quart of sweet milk in which has been beaten four or six " raw eggs." The Eradication of Texas Fever. — Since practically the tick alone spreads the fever, the extermination of the tick from a district frees that place from Texas fever. Removal of cattle from the infested range and persistent dipping will clean the cattle of ticks. Exclusion of cattle from a piece of infested territory for two winters and the intervening summer will free the place from ticks, which starve out for lack of a host. These measures are chiefly relied upon along the quarantine line to exterminate the tick, resulting in the removal of the line to a point south of the freshly-cleaned territory. The great difficulty in accom- plishing the work lies in the difficulty in persuading all stock owners to see the desirability and necessity of eradicating the tick, and in inducing them to work together.