Complete Retention of the Posterior Limbs 783 



smaller domestic animals, where the adjustment of the deviated 

 limbs or embryotomy is not available. 



3. Complete Retention of the Posterior I^imbs. 

 Breech Presentation. 



The breech presentation may be met with in any of the domes- 

 tic animals, and probably acquires its greatest significance in the 

 mare, where it constitues a very formidable cause of dystokia. It 

 differs from the preceding deviation in that, instead of being 



Fig. 136. Brbech Presentation. (St. Cyr. ) 



flexed at the hocks, the posterior limbs are flexed upon the 

 pelvis, beyond which each joint is in rigid extension and the 

 limbs are thrust forward beneath the abdomen and chest of the 

 fetus. The causes are identical with those of the preceding, and 

 probably in many cases complete retention follows flexion at the 

 tarsus. The flexed tarsus becomes caught against the brim of 

 the pubis, and the expulsive efforts of the mother, pushing the 

 fetal body along, cause the ossa calces to glide downward and then 

 forward, and the tarsus to become extended, until finally the en- 

 tire limb is pushed forward beneath the body. The operator, upon 

 examining the case, usually meets first with the tail or buttocks 



