ABNORMALITIES OP THE EXPELLING POWEUS 181 



In the parturient passages, another disturbance may occur, 

 which not only seriously interferes with expulsion, but also 

 endangers the life of the mother: inversion of the bladder, 

 with prolapsus of the inverted parts into the vagina. This con- 

 dition is very rare in the cow, as the bladder is firmly fixed by 

 the strong, fibrous pubo- vesical ligaments. It is recognized in 

 the vagina as a round, fluctuating tumor, about as large as two 

 fists, urine dropping from its surface. The aetiology, symptom- 

 atology and therapeutics are discussed in "Special Surgery." 

 Of course it is plain that the inverted bladder must be reduced 

 and kept in its place. Should the inverted prolapsed bladder 

 remain in the vagina, the passage of the calf would cause its 

 rupture and death of the mother. 



3. — Abnormalities of the Expelling Po-wer. 



In the expulsion of the foetus two factors are concerned : 

 the contraction of the uterine muscle and the auxiliary move- 

 ments of the muscles of the skeleton, known as abdominal 

 pressure. Where one or the other factor is not sufficiently 

 developed, the expelling forces become diminished, a condition 

 termedyee&?e jJO-ins. 



"When the action of the uterine muscle is diminished in 

 intensity, it is termed atonia uteri. This may be due to many 

 causes : excessive distention of the uterus from hydrallantois, 

 twins and emphysema of the foetus, by adhesion between the 

 uterus and adjoining organs, the result of a previous peritoni- 

 tis. Feeble pains may also be produced by paralysants, affect- 

 ing the nerve centres of the uterus. Thus the uterine contrac- 

 tions are feeble and occur at long intervals in cows suffering 

 with viti;lary fever either before parturition or at the time the 

 cervix uteri dilates. 



Abdominal pressure is lessened in hernia and pendulous 

 abdomens. In the latter instance the uterus is in the state of 

 anteversion, so that the expelling forces are acting in a direction 

 extremely unfavorable to the passage through the genital canaL 

 General weakness may also give rise to feeble pains. 



