2i6 Journal of Agriculture. [8 April, 1907 



during movement is not sufficiently pronounced to assist definitely to a 

 diagnosis. In such cases, diagnosis can be confirmed' or otherwise by the 

 hypoderaiic injection of a local anaesthetic over the course of the nerve 

 supplying the part suspected of being the seat of lameness. 



The operation is simple, and no bad results should follow, or swelling 

 remain, if ordinary antiseptic precautions are taken. Considering the 

 assurance which such a plan gives against the inevitable mistakes of guess- 

 work in diagnosing obscure lameness, it is surprising that it is not more 

 often adopted. Of course, a correct knowledge of anatomy — -the situa- 

 tion and course of the nerve to be injected — is fundamentally essential to 

 the success of the method ; without this the result may be oftentimes mis- 

 leading and disconcerting. 



The composition of the anaesthetic injection mav be varied, according 

 to the experience of the operator, but a mixture of cocaine and morphia 

 solutions is used with success. Twenty minims (drops), each of i in 10 

 solution of hvdrochlorate of cocaine and hydrochlorate of morphine, 

 mixed in 30 minims of sterilized water, would constitute such an injec- 

 tion. 



The injection should be made over the course of the nerve immediately 

 above the part suspected of being diseased. For instance, if the foot 

 is suspected, an injection is made on each side of the pastern over the 

 course of the internal and external digital nerves ; if the fetlock, the seat 

 of injection should be at the lower third of the metacarpal region (cannon 

 bones), over the inner and outer metacarpal nerves, or opposite the trans- 

 verse anastomotic branch joining the tw^o ner\es at the back ; if the 

 knee or splint bones, then inject at the bifurcation of the median nerve to 

 form the two metacarpals on the inner side of the forearm above the 

 knee, and also at the upper part of the bend of the knee, behind where 

 the cubital nerve bifurcates; and similarly in corresponding situations 

 when the hind limb is concerned. It is necessary to inject on both the 

 inner and outer aspects of the limb in all cases, because cocaine acts only 

 on the direct fibres with which it comes in contact. It has no action on 

 those nerve filaments ramifving in the part which are recurrent branches 

 of the opposite nerve, and which therefore still retain the power to 

 transmit painful impulses. If both sides are injected, however, both the 

 direct and recurrent fibres of each side are pre\ented from transmitting 

 sensation. 



Complete anaesthesia of the nerve and part should result within half 

 an-hour at the outside, but it often comes on within five or ten minutes ; 

 and this may be tested bv pricking the parts below with a pin or pen- 

 knife, when no sensation will be felt. If the suspicion as to the seat of 

 lameness has been correct, the animal should then be free from lameness. 

 If, however, lameness is still shown, and the injection h,as been properly 

 made, it may be safelv assumed that the speculation as to the seat of 

 lameness was wrong, and the operation should be repeated next day in 

 another suspected situation. The effects of the injection will pass off 

 in a couple of hours, and by that time sensation will have become re- 

 established, and the lameness will have returned and be as pronounced 

 as ever. 



SHOULDER LAMENESS. 



It is an impression commonly held bv " the man in the street," or the 

 horsey variety of that ilk, that lameness in the shoulder is of common 



