DISEASES OF ANIMALS 



119 



commonly known as red water, on ac- 

 count of the excretion of bloody urine 

 due to the destruction of the blood cor- 

 puscles. Texas fever was first men- 

 tioned in this country in 1S14 and grad- 

 ually attracted so much attention that 

 the Bureau of Animal Industry finally 

 took up the study of the disease, prov- 

 ing for the first time that it could be 

 transmitted only by means of the cattle 

 tick. It was soon found that south- 

 ern cattle are immune for the reason 

 that they become infested with ticks in 

 early life, developing a mild form of 

 the disease. A fever develops and the 

 animal becomes depressed and loses ap- 

 petite. Constipation is often observed, 

 followed by diarrhea. The red blood 

 corpuscles become dissolved to such an 

 extent that the coloring matter of the 

 blood appears in the urine during the 

 later stages. The first symptoms usu- 

 ally appear within nine to 14 days 

 and the disease is ordinarily fatal. The 

 Bureau of Animal Industry and a num- 

 ber of agricultural experiment stations 

 have perfected a means of producing 

 immunity by inoculating northern cat- 

 tle with the blood of recovered southern 

 cattle. For this purpose a small quan- 

 tity of defibrinated blood is used, and 

 after a period of eight or nine days an 

 inoculation fever appears, which persists 

 for seven or eight days, with an average 

 temperature of 104° F; after another 



Fig. 66 TEXAS FEVER QUARANTINE LINE 



period of 25 to 30 days, a second fever 

 period may appear for about a week. 

 Occasionally a third attack of fever oc- 

 curs. In 95 per cent of cases the results 

 are quite satisfactory in that treated 

 animals become perfectly immune. It 

 is best, however, to let them become in- 

 fested with ticks slowly after they are 

 shipped South. If tick-free pastures can 

 be found in the South, it is still better 

 \to ship the animals before inoculation. 



It has also been found possible to vac- 

 cinate cattle with blood obtained from 

 engorged ticks taken from southern cat- 

 tle. The ticks may thus be used as a 

 vehicle in which to ship the blood long 

 distances. 



Evers has had some success in inject- 

 ing hemoglobin into diseased cattle and 

 this treatment is based on the fact that 

 the hemoglobin, or red coloring matter 

 of the blood, is destroyed by the Texas 

 fever parasite and its replacement by 

 artificial means helps to tide the ani- 

 mals over the acute stage of the disease. 





Fig. 67 CATTLE TICKS 



FEMALE MALE 



Preventive measures — While the in- 

 oculation method is perfectly successful 

 in the vast majority of cases, it suffers 

 from certain disadvantages. It requires 

 for its successful operation the perpetu- 

 ation of the disease in the southern 

 states. Since it is *Certain that Texas 

 fever depends entirely upon the cattle 

 tick for its continuance, much attention 

 has been given lately to the problem of 

 eradicating the tick, and striking re- 

 sults have been obtained by Butler, 

 Morgan and others along this line. But- 

 ler has successfully eradicated the tick 

 from ten counties of North Carolina 

 and has placed these counties above the 

 quarantine line. Similar results have 

 been obtained in Tennessee, Louisiana 

 and elsewhere. The method of extermi- 

 nation is based on a system of rotation 

 of pastures and starvation of the ticks. 

 The ticks cannot live more than a year 

 without some animal blood as suste- 

 nance. For this reason a rotation of 

 pastures, with cultivation of the old 

 pastures, will gradually destroy the 

 ticks. In North Carolina it has been 

 found that this can be done at an ex- 

 pense of not more than $6.00 per farm. 

 The method appears to be so possible of 

 general application that an appropria- 

 tion has recently been made to enable 



