Flexion of the Hind Legs at the Tarsus 781 



2. Flexion of the Hind Limbs at the Tarsus. 



We meet occasionally, especially in the mare and cow, with 

 dystokia due to the tarsal articulations becoming flexed and 

 either entering the pelvic canal or becoming caught just in front 

 of the pubis. This displacement constitutes a formidable obstacle 

 to the expulsion of the fetus, because it necessarily involves the 

 flexion of all the articulations of the limb, and consequently 

 greatly increases the diameter as measured from the fetal sacrum 

 down through the folded limb. The femur is flexed upon the 

 pelvis, the tibia upon the femur, the metatarsus upon the tibia, 



Fic. 135. Rktextiox of Posterior Li.mrs at 



THK T.\RSUS. (FrANCK). 



and the phalanges upon the metarsus. We cannot extend one 

 of these articulations completely until the others are ready to be 

 simultaneously extended, and the folding of the limbs in this 

 manner quite effectively prevents the passage of a fetus of normal 

 dimensions through the pelvic canal. 



The diagnosis is comparatively easy. Upon inserting the 

 hand, the operator may first touch the tail, or the ischiatic tuber- 

 osities, lyying just beneath and in front of the pubic border, 

 there is recognized the summit of one or both hocks. In some 

 cases the flexed hocks extend into the pelvic canal. The fetus 



