BILATERAL DIGITAL NEUROTOMY 157 



existence of a mysterious predisposing diathesis, probably 

 a general abnormality of the bones, that contributes more to 

 the cause than the traumatisms previously enumerated. 



Aside from the disease known under the name of navic- 

 ular arthritis, digital neurotomy is indicated in lesions of the 

 same structure from direct wounds of the feet '(nail-pricks) 

 which have left a chronic lameness behind. In these cases 

 the lesion is usually a partial adhesion of the plantar aponeu- 

 rosis to the navicular bone, due to destruction by suppura- 

 tion of the navicular synovials. In these cases it is only 

 effectual when the lameness is not severe and when the 

 lesion is not very extensive. Hughes recommends digital 

 neurotomy very highly in side bones, for which disease he 

 resorts to the operation freely and without fear of disas- 

 trous consequences under any circumstances. 



The value of digital neurotomy depends upon the fact 

 that the superficial foot structures are not unnerved, and 

 that the hot bed of foot lesions is centered generally within 

 the structures receiving sensory impressions from the poste- 

 rior digital nerve. 



The ideal case of navicular disease for the operation is 

 the one wnth a slow progress that has never at any time been 

 manifested by severe lameness, with a tendency to point the 

 foot in the stall, and with a lameness marked enough when 

 first going out but gradually diminishing with exercise. The 

 foot may be somewhat smaller than normal and somewhat 

 contracted at the heels, without distracting any of the pros- 

 pects of a cure. The patient should, however, not be too 

 old. Digital neurotomy is much more effectual in the young 

 animal. 



RESTRAINT. — The operation can be performed in 

 either the standing or the recumbent position. The former 

 is advisable only when but one leg is to be operated upon, 

 as many patients become rather too restive before each of 

 the four nerves have been exposed and divided. The seat 

 of operation is anaesthetized subcutaneously by injecting 

 about thirty minims of a five percent solution of cocaine 

 hydrochlorate along the course of the nerve, some five to 

 eight minutes before the incision is made. A twitch is ap- 

 plied to the upper lip and an assistant supports the leg, 

 flexed backward as shown in Fig. 97. The operator sits upon 

 a low stool, kneels or leans forward at a comfortable distance 

 from the leg. 



The recumbent position is advised for operations upon 

 both legs and in restive animals. Either the casting har- 



