702 Veterinary Obstetrics 



The transudation involves the uterine walls also, causing them to 

 become immensely thickened, injected and black ; the maternal 

 and fetal placentae undergo analogous changes; the fetal mem- 

 branes become involved ; and e'xtensive exudation of bloody 

 serum occurs in the uterine, allantoic and amniotic cavities, in- 

 creasing enormously the volume and weight of the gravid organ. 



It is said that in some cases the fetus undergoes mummifica- 

 tion, but if this occurs it must be very rare. The tendency is 

 rather for infection, of the uterus and its contents to take place 

 and lead to putrid decomposition. Under normal conditions, 

 the cervix uteri acts as an efficient guard against infection. The 

 cervical canal is hermetically sealed with a mucous plug. When 

 torsion occurs, the tissues of the vagina and cervix at once lose 

 their normal function and, when the torsion is extreme and the 

 vitality of the walls becomes depressed or destroyed, their 

 bactericidal power declines or ceases, and they serve rather as a 

 favorable culture ground for bacteria, which consequently ad- 

 vance to the uterus and its contents, either along the cervical 

 canal or through the tissues, and thus cause fetal decomposition 

 and septic metritis. 



It has been stated by some veterinary obstetrists that the 

 torsion of the uterus may take place at any point, or nearly so, 

 in the entire organ in the vagina, the cervix or body of the 

 uterus, or in the cornu. . A stud}' of the figures presented will 

 answer this question. If we examine the gravid uterus, as shown 

 in Figure 114, and revolve it upon its long axis, as has been 

 done in 115 and 116, we find that we are dealing essentially with 

 a large bag, containing solid (fetus) and liquid contents, in 

 which the fundus of the uterus or the gravid cornu represents 

 the bottom pf the sac, while the cervix and vagina rfepresent the 

 closed mouth, which is fixed to the immovable vulva. 



Attempting to revolve this bag upon its long axis, we at once 

 find that it will twist only at or near its point of fixation, where 

 its mouth has been closed. If the uterus were empty, it could 

 admittedly twist at any point throughout its entire extent, but 

 when completely filled this cannot occur. Instead, if it were 

 forcibly revolved and forced to begin to twist in this part, it 

 would be torn asunder because the contents do not permit of 

 any decrease in volume. Therefore, in cases of uterine torsion 



