Complete Retention oj 'Anterior Li?nbs 765 



c. Deviations of the Head and Neck. 



In domestic animals, the tendency for the head to become more 

 or less deviated at the time af birth varies greatl}^ because of the 

 differences in the length of the neck as compared to its transverse 

 diameter. In the pig, where the neck is thicker than its length, 

 it is verj^ difficult for the head to become deviated, in marked 

 contrast to the foal, with the very long and slender neck, in which 

 these deviations are among the most common and serious forms of 

 dystokia. Not only is the head of the foal very liable to deviation 

 at the time of birth, but frequently the head and neck have be- 

 come bent laterall}' at a very early date in gestation and have re- 

 mained so throughout the development of the fetus, constituting 

 a serious deformity — wr^'-neck. 



I. Lateral Deviation of the Head. 



The most common form of deviation of the head is the lateral, 

 as it is in this direction that the neck is most flexible and the 

 head most readily displaced. The deviation may occur with 

 equal facility to the right or the left. 



The causes of lateral deviation of the head are two. In the 

 foal the deviation frequently occurs during an early period of 

 gestation, to constitute wry-neck, so that when the end of gesta- 

 tion arrives the head and neck have already been doubled back 

 along the side of the foal for weeks or months, the parts have 

 become thoroughly adapted to this position, and the head lies in 

 the flank of the foal, where it is moulded to the convex surface 

 of its body. That side of the head in contact with the body of 

 the foal is concave, and the opposite side convex. 



The second, and except in the foal, perhaps the only cause of 

 deviation, and the one which is most subject to remedy, is an 

 accidental misdirection of the head at the time of the parturition. 

 As the fetus, in an anterior presentation, is being forced along 

 the genital canal, the nose or other portion of the head becomes 

 somewhat deflected to the right or the left, and, becoming im- 

 pacted against some projecting portion of the pelvis or genital 

 canal or entangled in some way in the fetal membranes, is drawn 

 farther to one side, until it becomes caught between the side of 

 its body and the wall of the uterus or vagina. When this oc- 

 curs it is highly improbable that delivery can proceed spontane- 

 ously, but instead the head tends to become farther and farther 



