566 DISEASES OF THE HOESE. 



tion in cattle. These are especially by ingestion ; that is, by taking up 

 the germs with the feed, water, or other means, which have become 

 contaminated with the germs. The infection through the genital 

 organs is probably not so frequent, but in this regard the stallion no 

 doubt plays an important role in the spreading of the disease. Scho- 

 field considers this method of infection as the principal source of 

 spreading the disease. 



It must be considered that in infected stables the germs may be 

 present throughout the premises, and by keeping animals which have 

 aborted in such stables a contamination of feed and utensils may con- 

 tinually take place, since the aborted mares usually discharge a con- 

 siderable quantity of material which is often heavily charged with the 

 germs. The germ is taken up by the body with the feed or water, 

 passing from the intestines into the blood, and from there is carried 

 to the genital organs, where it finds suitable conditions for its de- 

 velopment. Milk from an infected mare may also contain the germ, 

 and colts may become infected by sucking the milk of infected 

 mothers. In such instances the infection may remain dormant until 

 the colt develops and becomes pregnant, when the organism, finding 

 a condition suitable for its development, produces the disease. 



On the other hand, stallions used in covering infected mares may 

 be carriers of the germs, and when used for the breeding of healthy 

 animals may in this manner readily transmit the disease to them. 



Diagnosis. — Contagious abortion may be diagnosed by the changes 

 which occur in the fetal membranes, and also in the expelled feces. 

 In order, however, to substantiate a diagnosis with certainty, demon- 

 stration of the germ by miscroscopical examination is necessary. 

 The occurrence of frequent abortions among the mares in a stable is 

 also an additional evidence of the contagious character of the mal- 

 ady. It must be considered that at times infected mares may carry 

 the fetus to full maturity, in which case the diagnosis is possible only 

 by blood examinations in a laboratory. 



Infected animals usually abort only once; however, in a certain 

 proportion of cases they may abort even two, three, or four times in 

 succession. 



Animals which establish a tolerance for the infection, and carry 

 the fetus to full maturity, may nevertheless remain a source of dan- 

 ger for spreading the disease. 



The tests used in laboratories for the diagnosis are the agglutina- 

 tion and complement-fixation tests, by which the disease may be diag- 

 nosed from a sample of blood from a suspected animal. Such tests, 

 however, have to be confined to the laboratories, which are equipped 

 for such work. 



Treatment and prevention. — Medicinal treatment is usually of no 

 avail, and all efforts should be directed toward the prevention of the 



