126 OPERATIVE TECHNIQUE. 



where no such operating table is at hand to cast the animal. 

 In operating on the external surface of a limb, the horse is cast 

 on the opposite side. If the application is made around a joint, 

 the animal should be cast on the diseased side and the inner 

 face of the limb first operated on. In firing two limbs, the external 

 surface of the one limb and the internal of the other are first 

 completed, and when turning the animal over provision must be 

 made against the cauterised surfaces being soiled. 



Various manoeuvres are sometimes necessar}-. As a rule the 

 limb to be fired is left in the hobbles, while the opposite limb is 

 released and either carried backward or forward. When the pastern 

 or coronet is to be fired, the two limbs can be fastened together 

 above the knee or hock respectively, the diseased limb being 

 released from the hobble and drawn forward or backward by an 

 assistant using a broad strip of webbing. 



The important point is to trace equally spaced straight lines, 



and to extend beyond the diseased region. Converging lines should 



never cross or unite, the points of crossing being ver}' liable to 



slough (see Fig. 152). The spaces between the lines vary according 



, y to the thickness of the skin and the extent of the 



\ / cauterised region. Closely placed superficial lines 



\^i/ are preferable to others more distant and more 



\ / deeply penetrating, x^s a rule a space from three 



eighths to three fourths of an inch should divide 



Fig. 152. — Pattern for ,1 ,• t t- ^\ ^ • n ^ ^ t 1 ^i 



line firino". The lines the Imes. In r rance the custom is first to lightly 



do not meet. mark out the design, and afterwards to pass over 



the lines a number of times. The iron is used at a dull or bright red, 



the latter being the maximum temperature allowed, and is passed 



slowly along the marked-out design without pressure, the blade of the 



cautery being always kept perpendicular to the surface. The iron 



should never be passed twice in immediate succession along the same 



line, and if the French method be adopted, the lines must be retraced 



in regular order, otherwise sloughing is apt to occur. When the 



cauterised surface is very small, it is well to wait for a short time 



between the first and second series of applications. 



The operator judges when the cauterising action is sufficient by 



the appearance of the base of the lines, the exudation which has 



occurred, the infiltration of the skin, and the degree of separation 



shown by the epidermis. Judged b}' these standards, three degrees 



of cauterisation may be distinguished. In the first the lines are 



shallow and contain a few little drops of serosity. Their base is 



of a golden yellow, the skin is little infiltrated, and the epidermis 



