478 Veterinary Obstetrics 



inarians began to hold that the prevalence of the disease was due 

 to infection and not to climatic or other chance influences acting 

 upon a great number of animals, in the same way, at the same 

 time. 



Infectious abortion of mares first acquired prominence in the 

 United States about 1886, when it appeared in several states in 

 the Mississippi Valley, in which horse breeding had become a 

 very important industry. It soon acquired a very extensive dis- 

 tribution and high degree of virulence. The unorganized state 

 of veterinary science in the United States prevented the recording 

 of any definite statistics in reference to the losses, but they were 

 certainly enormous. At the time of the introduction of this dis- 

 ease, or rather when it acquired general importance, the writer 

 was in private practice at Bloomington, 111., which was then one 

 of the richest draft horse breeding districts in America, and we 

 estimated that in 1888, in one county, at least 2500 foals perished 

 from infectious abortion. Since these foals were generally valued 

 at about $60 per head at weaning time, the monetary loss may 

 be estimated at $150,000 in a single year in one county. That 

 county was in no way essentially different from others through- 

 out a number of states. 



Were reliable statistics as to the actual losses available, they 

 would be so enormous for the entire Mississippi Valley as to be 

 astounding. In some townships where horse breeding constituted 

 one of the principal agricultural pursuits, the abortions exceeded 

 seventy-five per cent of the pregnant mares. The losses were 

 most marked in large breeding establishments where highly 

 valuable mares were kept for breeding purposes alone. The 

 losses were just as real on small farms where but a few mares 

 were kept, which, after aborting, could be employed to some 

 extent in farm work. However, throughout this area, many 

 farmers maintained a number of mares wholly for the purpose of 

 breeding. In such herds, the losses of the foal crop were often 

 complete. In one season, one of our clients with a highly valu- 

 able herd of imported draft mares, about 50 in number, lost every 

 foal from infectious abortion, save in the case of one mare, which 

 was in our hospital under treatment for a chronic disease and 

 consequently carried her foal to full term. In another instance, 

 in the territory of a neighboring veterinarian, a breeder had 100 

 pregnant imported draft mares, in which the loss from infectious 



