DYSTOKIA DEPENDING ON POSTERIOR PRESENTATION. 475 



sacral presentation ; but in pushing the exploration further, and follow- 

 ing the cannon bone with the hand, the hock is met with — recognizable 

 by lis fatness on each side, t\\Q pomt of the hock downwards, the /5<f«^ being 

 upwards in the same direction as the wall of the hoof ; whereas the bend 

 of the knee is in the same direction as the sole of the foot. Beyond the 

 hock the hand also comes in contact with the croup and the tail, lying 

 towards the maternal pubis. 



The obstacle to birth lies chiefly in the thighs and buttocks, while the 

 hind-feet project against the mother's sacrum, and, in addition to increas- 

 ing the resistance, threaten to lacerate the organs interposed between 

 them — the vagina or rectum, or both — and that bony mass. Besides this, 

 the body of the foetus itself in this position forms a curve exactly the 

 reverse of that of the pelvis ; so that it cannot readily accommodate itself 

 to the bony canal through which it should pass. From all these causes 

 this position is not only unfavorable to birth, and must be remedied, but 

 it may also lead to serious accidents. 



The position appears to be more frequently met with in the Mare than 

 the Cow, Donnarieix having witnessed it at least a score of times in the 

 first-named animal. This authority, however, is of opinion that it is 

 altogether a secondary position : the foetus at the commencement being in 

 a normal position (lumbo-sacral), and still alive, is retained at the pelvic 

 inlet by its croup, and soon dies ; them obeying the laws of gravity, at a 

 moment when the uterus is relaxed, it turns upside down. And he gives 

 what he considers a proof, in the fact that breeders, in consequence of 

 what he was always telling them,. — to the effect that in the posterior 

 presentation the foal does not live for longer than half an hour, were 

 always successful in bringing the young creature forth alive when they at 

 once resorted to traction in such cases : all informing him that the croup 

 was above and the belly below ; while in all the instances in which he had 

 to interfere, the belly was upper7nost and the back dowmvards. In the 

 latter cases Donnarieix never found the foal living. 



Saint-Cyr, however, thinks this explanation is not quite satisfactory, 

 that the opinion is too absolute, and that in the Mare, as well as in the 

 Cow, the lumbo-pubic position of the foetus may very well h^ primary. 

 Donnarieix himself admits as much, from a case recorded by Rochard, in 

 which a living foal was extracted — an extremely rare event in the equine 

 species. 



Indications. 



The nvajority of authorities recommend that rotation of the foetus 

 should be practised in this position, so as to convert it into a licmbo-ilial 

 or even a lumbo-sacral position ; while others, and notably the French 

 veterinary obstetrists, do not think of changing the position, but readily 

 effect delivery when other causes of dystokia do not complicate it — in- 

 deed, they look upon these cases as the easiest to remedy, and rarely 

 requiring more than a quarter of an hour. 



The most important matter for attention is the direction of the hind- 

 feet during delivery ; these should be carefully guided through the genital 

 canal until they are external to the vulva, so as to avoid those lacerations 

 and ruptures which are only too readily produced. 



In order to accomplish delivery, the pastern of each hind-limb should 

 be corded ; then the hand should be glided along the flexor tendons until 



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