DYSTOKIA DEPENDING ON POSTERIOR PRESENTATION. 477 



The malposition of the hind-limbs may be cf three kinds: i. Flexed 

 fetlocks, projecting either against the brim of the maternal pelvis, or 

 jammed against some part of the genital canal ; 2. Flexed hocks, the 

 doubled limbs engaged more or less deeply in the passage; 3. Hind- 

 limbs completely retained in the uterus, and applied more or less closely 

 against the abdomen of the foetus, the back part of the thighs and the 

 croup presenting at the inlet. 



We have mentioned that one or both limbs may be in a vicious posi- 

 tion ; even when the two are misdirected they may not be in the same 

 deviation — one leg being perhaps flexed at the hock and the other 

 extended forward towards the chest, one flexed at the fetlock while the 

 other is bent at the hock, etc. 



Fetlock Presentation. 



This abnormal direction of the hind-limbs is not frequent, and when 

 encountered is not of much importance, so far as obstetrical skill is con- 

 cerned. The misdirection of the phalanges can be quickly detected by 

 exploration, and corrected as follows: — Extension of the pastern is 

 accomplished by pushing the entire limb forwards into the uterus, and 

 bringing the fetlock towards the vulva by seizing it at that joint — the 

 fingers forwards, and the hollow of the pastern and heels of the hoof in 

 the palm of the hand. By closing the hand and tightening the fingers, 

 the pastern is extended and the foot carried towards the canal. The 

 end of the limb is now corded, and if the other fetlock is in a like condi- . 

 tion, it is adjusted in the same manner, and delivery effected. 



Hock Presentation, 



The mechanism of hock presentations is supposed to be as follows : — 

 The foetus, in the posterior presentation, and impelled by the uterine 

 contractions towards the cervix, reaches the inlet with the hind-limbs not 

 quite extended, nor the axis of the young creature quite coinciding, per- 

 haps, with that of the passage. Consequently, the legs come in contact 

 with the pelvic brim below by the posterior surface of the shank, while 

 the croup encounters the sacro-vertebral angle above. 



The labor-pains continuing, the croup has a tendency to descend, and, 

 with the points of the hocks, to advance through the os : the latter joints 

 become gradually flexed until at last the cannon-bones press against the 

 thighs, and the doubled legs and croup, jammed in the inlet, form far too 

 large a mass to advance further (Fig. 133). Labor is therefore sus- 

 pended, and the animal becomes exhausted with futile straining. 



The increase in volume is well exemplified in the annexed outlines 

 (Fig. 134). 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^ P) in its usual position. The consequence, in figure 

 A, is apparent in the elevation of the stifle to the middle horizontal line, 

 and the 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 different. 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 



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