108 THE EXTERIOR OF THE HORSE. 



ordinarily on the lateral faceSj along the course of the jugular gutter, and on the 

 borders. 



On the lateral faces there are sometimes traces of setons, which occupy the 

 superior third of its length. These are very significant, because they indica^;e 

 that the animal has been treated for disease of the eyes, the nasal sinuses, or the 

 encephalon, as vertigo. 



Along the course of the jugular vein there are traces of firing and linear cic- 

 atrices, which suggest that the horse has been affected with inflammation of the 

 jugular vein, or that he has undergone a serious operation in this region. It is 

 important, then, to determine if one of these veins is not obliterated. To ascer- 

 tain this it is sufficient to make pressure with the thumb over its course at the 

 inferior part of the neck, in order to prevent the blood from descending towards 

 the heart. The slight shake of the hand will reflect the waves of the column of 

 blood to the upper extremity of the gutter when the vein is intact. The contrary 

 effect will show that the vessel is obliterated and the circulation is re-established 

 by collateral vessels. If the obliteration exists only in one of the jugulars, the 

 inconvenience is not so great, because the circulation is still sufficiently active 

 through the one of the opposite side. When, however, the obstruction exists on 

 both sides, the animal is unfit to perform rapid service, because the collateral veins 

 are insufficient for the afferent circulation, and congestion of the component j^arts 

 of the head is the consequence. Moreover, the jugular vein being the vessel 

 selected for phlebotomy, we are not able, under this circumstance, to have 

 recourse to it in cases of emergency. 



Very frequently the bleedings, of which one of the veins has been the seat, 

 leave their trace on the skin. A very small longitudinal cicatrix indicates the 

 spot where the tissues have been involved by the fleam of the operator. At 

 other times these traces are more apparent, manifesting themselves by varicose 

 dilations, simple or multiple, along the course of the vein, at the level of the 

 places where it had been punctured. This condition is called varicose. 



Along the inferior border we recognize cicatrices resulting from trache- 

 otomy, — that is to say, the artificial opening of the trachea for the prevention of 

 asphyxia when the natural air-passages are occluded or have an inadequate calibre. 

 It is necessary, in a case like this, to exercise the animal in every possible way to 

 determine whether he is or is not a roarer. A horse that carries a tracheal tube 

 permanently will almost completely lose his value, and should not be purchased. 



We observe, also, along the inferior border of the neck, surfaces flattened 

 from before to behind, arising from fractures of the cartilaginous rings of the 

 trachea, or from a congenital deformity of the conduit, which infringe on its 

 sides, and always diminish, in the same proportion, its internal calibre. Occa- 

 sionally, difficulty of respiration arises in consequence of this affection, and we 

 should fully satisfy ourselves as to the manner in which respiration is effected in 

 horses with such a deformity. 



Finally, the superior border of the neck may present cicatrices following 

 deep abscesses with necrosis of the nuchal ligament, a'disease which requires a 

 long time to recover from, and which should never be passed unobserved. These 

 blemishes are ordinarily occasioned by the use of a collar too small or improperly 

 fitted. 



From the same causes appear calluses and corns along the anterior border 

 of the shoulder, or in the vicinity of the superior border of the neck. 



