COMMON AILMENTS OF CATTLE 329 



result. It is also well known that ergot may cause wide- 

 spread abortion in cows. This fungus is seen as black, hard, 

 spurlike growths that protrude from the seeds of grasses 

 at the time of ripening. Rye grass is especially subject to 

 ergot, and it is common in blue grass, especially in low wet 

 places. 



When a single case of abortion occurs in a herd, it is to 

 be attributed to some accidental cause. If a number occur 

 near together, the cause is occasionally to be looked for in 

 ergot in the feed. More often it is due to the presence of 

 the contagious disease. 



Contagious Abortion. This disease causes more loss 

 financially to the dairyman of the country than any other to 

 which cattle are subject. Investigations show that this trouble 

 is brought about by the presence of living germs, in the 

 genital organs of the cow, which bring about a condition that 

 causes the premature expulsion of the calf. That it is con- 

 tagious is shown by the spread through a herd from an 

 infected animal that has been brought in, and by experi- 

 mental inoculation. From 50 to 75 per cent of the cows in 

 a herd usually are affected. The remainder seem to be 

 naturally immune. The fetus is usually expelled at the 

 sixth or seventh month. As a rule, no marked disturbance 

 of the animal's health occurs. In most cases the usual 

 signs of normal parturition appear, as enlargement of the 

 udder and vulva. When the cow is already in milk, no 

 symptoms may be noticed. After having once aborted, a 

 certain proportion of the cows will abort a second time, 

 usually carrying the calf a little longer than the first time, and 

 after this seem to become immune and do not again abort. 

 Others, as a result of abortion, become sterile or shy breeders. 



