INFECTIOUS DISEASES OF CATTLE. 487 



By infesting with, ticks. — Immunity may also be induced in suscep- 

 tible animals by placing a limited number of fever ticks upon their 

 bodies in order to produce the disease naturally. For this purpose 

 only animals less than 1 year of age should be used, as the method is 

 not applicable for older and more susceptible animals. Upon the 

 bodies of these young cattle from twenty- five to fifty seed ticks should 

 be placed, which in the course of about ten days will occasion a rise 

 of temperature and a mild form of Texas fever. . When the animal 

 has entirely recovered from this attack, a second crop — double the 

 number first used — should be applied to the animal in order to in- 

 crease its power of resistance when pastured on infested soil. In 

 order to carry out this method successfully, a constant supply of seed 

 ticks must be at hand. This can be accomplished by placing the 

 mature females in a Mason fruit jar among some dirt and leaves and 

 keeping them in a warm place. In a few weeks the eggs will have 

 been laid and hatched, and a number of seed ticks will be present for 

 use in infesting the cattle to be immunized. By placing a few adult 

 females in the jar every two months there will always be a supply of 

 these young ticks. This method of producing immunity by controlled 

 tick infestation is not so safe as blood inoculation, since the quantity of 

 germs injected can be more accurately regulated by means of a syringe. 



Treatment. — When the disease has broken out, all animals, the 

 sick as well as the healthy, should at once be removed to another 

 noninfected pasture. While this may not cut short the disease, it 

 may save the lives of some by removing them from the possibility of 

 being attacked by more young ticks. Removal from infected pas- 

 tures likewise prevents a second later attack in October or early in 

 November, which is caused by another generation of ticks. It is true 

 that sick natives 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, as far as this is possible, 

 from sick animals, since they abstract a considerable amount of 

 blood and thereby retard the final recovery. 



Medical treatment of the sick has generally been unsatisfactory, 

 although in chronic cases and those occurring late in the fall bene- 

 ficial results have followed. If the animal is constipated, a drench 

 containing 1 pound of Epsom salts dissolved in 1 quart of water should 

 be administered, followed by the sulphate of quinine 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 whisky or alcohol 2 ounces may be combined with the qui- 

 nine according to indications of individual cases. An iron tonic con- 

 taining reduced iron 2 ounces, powdered gentian 4 ounces, powdered 

 nux vomica 2 ounces, powdered rhubarb 2 ounces, and potassium 

 nitrate 6 ounces will be found beneficial in the convalescent stage 



