364 PRINCIPLES OF VETERINARY SURGERY 



are made, but this precaution is hardly necessary in view of the extremely 

 short duration of the operation. Special irons are required to obtain the 

 best results. They should be shaped like a drum-stick, with a head about 

 one inch to one and a half inches in diameter. Only the head is heated, 

 and the handle, before plunging the head into the wound, should be cooled 

 completely with cold water, to prevent burning the skin and superficial tis- 

 sues. With this latter precaution it is indeed remarkable how painless the 

 operation really is. Only the first plunge causes a slight resistance. The 

 virtue of this technique depends, not alone upon the sloughing of the tumor. 

 It seems that the intense heat to which the surrounding parts are submitted 

 terminates the degenerative process in the tissues, and at least thoroughly 

 disinfects them. — L. A. M. 



ANNOTATION. 



Thecal Abscess of the Horse. 



The term "thecal abscess" is the appropriate appellation for a number of 

 special lesions of the horse, consisting of accumulations of purulent products 

 m great tendon sheaths. They are found chiefly in the navicular sheath, 

 the sesamoidean sheath, the tarsal sheath, and occasionally in the carpal 

 sheath. Other sheaths (those of the extensors) are also frequently affected, 

 but only the larger ones are of any serious consequence in this connection. 

 These suppurations are of sufficient frequency and seriousness to require 

 special mention in the study of abscesses. In the sheaths of tendons con- 

 cerned in supporting weight, (the sheaths of the flexors) abscesses are at- 

 tended with grave consequences, that either prove fatal, produce permanent 

 blemishes and lameness or at least run a troublesome course of long dura- 

 tion. 



Etiology. — Sheath abscesses are always traumatic. They are due to 

 the introduction of infective matter into the synovial membrane through 

 abrasions, punctures or contusions. They are rarely ever secondary ab- 

 scesses. In the colt, secondary articular abscesses occur from navel infec- 

 tion, but in these cases the sheaths are never implicated except through their 

 contiguity to the purulent articulations. Sheaths may, however, become in- 

 fected from one another by the spread of an infective inflammation from 

 below upward in the affected limb. Abscess of the navicular sheath due 

 to a nail prick, may thus, in rapid succession, attack the sesamoidean and 

 the tarsal sheaths, by encroaching upwards along the tendons. This spread 

 of the disease is, however, limited to very acute infections. The usual thecal 

 abscess remains quite tenaciously isolated within the limits of the synovial 

 membrane that sustained the initial injury. 



Abscess of the navicular sheath is generally caused by the nail wound 

 that penetrates into its synovial membrane. In some instances it follows the 

 apparently trivial nail puncture, owing to the encroaching tendency of the 

 infective inflammation, so thoroughly confined beneath the hoof. These 

 abscesses also follow gangrenous dermatitis (furunculus) in the region of 

 the heels. The sloughing of patches of skin often opens channels for the 

 borrowing of purulent products downward into the synovial membranes in 

 the region, and thus creates a serious synovitis with all its attending results. 

 In this manner the sesamoid sheaths are frequently infected. These struc- 

 tures are, however, most frequently injured from interfering. The contused 



