MUllBID ALTKIIATIUXS IX THE (JEXERATIl'E OliGAXS. 365 



When the os has been considered sufliciently dilated for the intro- 

 duction of the hand and arm into the uterus, then the foitus should be 

 placed in position for extraction — the most favourable bein^', of course, 

 the vertebro-sacral, with the head and fore-limbs towards the os. 

 Should it be found impossible to engage these in the passage, tlien 

 more incisions may be made in the cervix, and this can be done with- 

 out displacing the foetus. 



It is well to remember that it is very much better to dilate the os by 

 incision than by laceration, through unduly forcing the foetus into it. 

 At the same time, judicious traction should be made during the maternal 

 eflbrts. 



Aubry, Van Dam, and some others, have witnessed fatal haemorrhage 

 resulting from the incisions ; while metro-peritonitis has also been 

 reported as an equally unfortunate sequel. 



But these cases are exceptional. Those veterinary obstetrists in this 

 country and on the Continent who have had most experience in the 

 operation, are unanimous in asserting that, provided certain pre- 

 cautions are adopted in making the incisions, no such results are likely 

 to follow. 



Donnarieix states that, in thirty years, he has performed vaginal 

 hysterotomy in sixty cases of schirrus and other kinds of induration 

 of the cervix leading to occlusion of the os uteri, and of these only one 

 (Jied, though the cause of death was not ascertained. Recovery is the 

 rule and death the exception. 



Of course, recovery must always be doubtful if the disease of the 

 cervix is of a malignant nature, as the operation and the irritation caused 

 by the extraction of the foetus will, in all probability, hasten its progress. 



In some rare instances it may be advisable to have recourse to the 

 Caesarian section at once. When, for example, labour has been severe 

 and prolonged — when some days have elapsed since parturition com- 

 menced, and the veterinary surgeon is not sent for until amateurs have 

 exhausted their efforts and the animal is sinking; or when, from a 

 vaginal exploration, it is ascertained that uterine or vaginal disease is 

 so extensive and advanced that the mother cannot live much longer, 

 and the foetus is alive ; then this formidable operation should be adopted 

 without delay. 



4. Complete Ohliteuation (Atresia) of the Os Uteri. 



Congenital atresia of the os uteri may at once be admitted as an 

 impossibility in obstetrics, as if this canal is completely closed impreg- 

 nation cannot take place. But between fecundation and parturition 

 certain alterations may occur which, by leading to more or less persis- 

 tent closure of this passage, will prove an obstacle to birth. These 

 alterations may indeed exist at the period of fecundation, but then the 

 uterine opening must be only partially closed ; and, in fact, at parturi- 

 tion the OS may be superficially and partially, as well as completely, 

 occluded. This condition has been observed in the Mare, Cow, and 

 Sheep. 



Causes. 



The occlusion may be due to agglutination of the walls of the os, 

 the formation of fibrinous membranes or bands, the development of 

 cicatricial tissue from wounds or injuries sustained in previous preg- 

 nancies, etc. 



