ABNORMAL POSTERIOR PRESENTATIONS. 1(53 



joints become <;raclually tloxed until at last the cannon-bones press 

 against the thighs, and the doubled legs and croup, jannned in the 

 inlet, form far too large a mass to advance further (Fig. 139). Labour 

 is therefore suspended, and the animal becomes exhausted with futile 

 straining. 



The increase in volume is well exemplified in the annexed outlines 

 (Fig. 140). In figure A, we observe that the direction of the femur 

 (a b) is much more oblique than in figure B, which shows the limb 

 extended, and that bone {a b') in its usual position. The consequence, 

 in figure A, is apparent in the elevation of the stifle to the middle 

 horizontal line, and tlie inclusion of the hock and greater portion of the 

 metatarsal bone in the line below, which only touches the stifle {a b', 

 figure B). 



The mechanism is quite the same in the lumbo-pubic and lumbo- 

 ilial positions, the parts of the pelvic brim against which the croup and 

 limbs impinge being alone ditierent. One limb only may be retained in 

 this malposition, as already remarked, the other being extended in a 

 normal manner ; but this does not in any way alter the state of affairs 

 — neither with respect to the mechanism, nature of the complication, 

 nor measures to be adopted. 



In hock presentation, the point of the os calcis is always the first 

 part the hand encounters in exploration ; but it may be found at various 

 depths. Sometimes the hocks alone are in the canal, the body of the 

 foetus being still in the uterus ; while in other cases they and the croup 

 are within the inlet, and are wedged in the passage. But it is not so 

 much these which form an obstacle to birth, as the phalanges of the 

 hind-limbs, which, owing to the extreme flexion of the hocks, are flexed 

 to a corresponding degree, and so form two hooks which cling to the 

 edge of the pubis. Consequently, birth is impossible without extraneous 

 aid. 



Indications. — The difliculties vary according to circumstances. With 

 the larger animals at their full period of pregnancy, birth cannot take 

 place, as a rule, until the deviation has been rectified ; and to attempt 

 delivery before this has been done is to expose the Cow or Mare — 

 particularly the latter — to great danger. With the Sheep, Goat, 

 Sow, and Bitch, the fcEtus can be, and often is, extracted in this mal- 

 position. 



The indication is, therefore, with the Mare or Cow, to give the hind- 

 limbs a favourable direction, by extending tliem in the genital canal ; 

 and this is more easily accomplished in the Cow than the Mare, owing 

 to the smaller size of the croup and shorter limbs of the Calf. Some 

 authorities are even of opinion that the latter may at times be extracted 

 without the limbs having been adjusted ; while others assert positively 

 that delivery may be effected in the Cow by nmtation of the fcetus, but 

 that this is impossible with the Mare, unless a particular operation — 

 to be noticed immediately — is adopted. Saint-Cyr, however, has. with 

 more or less trouble, and the Mares not straining severely, succeeded on 

 four or five occasions, when the Foal made a hock presentation, in ex- 

 tending the limbs in the genital canal, and effected delivery without 

 resorting to this operation. He points out, nevertheless, that the Foal 

 dies very quickly in this position, while very often the Calf is extracted 

 alive, even after long and laborious manipulations. Other writers 

 corroborate Saint-Cyrs opinion with regard to deUvery. 



