SIXTH ANNUAL YEAR BOOK — PART VIII. 631 



Abortion in cows is eitlier contagious or noncontagious. It doe3 

 not follow that the contagmm is the sole cause in every case in which 

 it is present. We know that the organized germs of contagion vary 

 much in potency at different times, and that the animal system also 

 varies in susceptibility to their attack. The germ may therefore be 

 present in a herd without any manifest injury, its disease producing 

 power having for the time abated considerably, or the whole herd 

 being in a condition of comparative insusceptibility. At other times 

 the same germ may have become so virulent that almost all pregnant 

 cows succumb to its force, or the herd may have been subjected to 

 other causes of abortion which, though of themselves powerless to 

 actually cause abortion, may yet so predispose the animals that even 

 the weaker germ will operate with destructive effect. In dealing with 

 this disease, therefore, it is the part of wisdom not to rest satisfied 

 with the discovery and removal of one specific cause, but rather to exert 

 oneself to find every existent cause and to secure a remedy by correct- 

 ing all the harmful conditions. 



CAUSES OF NONCONTAGIOUS ABORTION. 



As abortion most frequently occurs at those three-week intervals 

 at which the cow would have been in heat if nonpregnant, we may 

 assume a predisposition at such times due to a periodicity in the ner- 

 vous system and functions. Poor condition, weakness, and a too watery 

 state of the blood is often a predisposing cause. This in its turn may 

 result fi'om poor or insufficient food, from the excessive drain upon the 

 udder while bearing the calf, from the use of food deficient in certain 

 essential elements, like the nitrogenous constituents or albominoids, from 

 chronic wasting diseases, from roundworms or tapeworms in the bowels, 

 from flatworms (fiukes, trematodes) in the liver, from worms in the 

 lungs, from dark, damp, unhealthy buildings, etc. In some such cases 

 the nourishment is so deficient that the fetus dies in the womb and 

 is expelled in consequence. Excessive loss of blood, attended at it usually 

 is by shock, becomes a direct cause of abortion. 



Acute inflammations of important organs are notorious causes of 

 abortion and in most contagious fevers (lung plague, rinderpest, foot- 

 and-mouth disease) it is a common result. Affections of the chest 

 which prevent due aeration of the blood induce contractions of the 

 womb, as shown experimentally by Brown-Sequard. Pregnant women 

 suffocated in smoke aborted in many cases. 



Chronic diseases of the abdominal organs are fetile sources of 

 abortion, especially those that cause bloating (tympany of the first 

 stomach) or diarrhea, or the diseases of the ovaries, kidneys, or bladder. 

 The presence of gravel, or stone, in the kidneys, bladded, or urinary 

 canals is an especial predisposing or even an exciting cause in mag- 

 nesian limestone districts and in winter. The presence of tubercles in 

 the ovaries, the broad ligaments of the womb, and even on the outer 

 surface of the womb itself, must be added as efficient causes. 



