Anaesthesia ensues in from six to twenty minutes, and if the cause of the lameness is below the point of injection the animal moves sound.

Regarding this method of diagnosis, Professor Udriski of Bucharest, after a series of trials, sums up as follows: 

1.  For the diagnosis of lameness cocaine injections are of very considerable value.

2.  These injections should be made along the course of the nerves.

3.  Solutions heated to 40 deg. or 50 deg.  C. produced quicker, deeper, and longer anaesthesia than equally strong cold solutions.

4.  In the sale of horses cocaine injections conceal fraud.

Cocaine being an irritant, it must be remembered that after the anaesthesia the lameness is somewhat more marked than before.

To the cocaine other practitioners add morphia in the following proportions: 

Cocaine hydrochlorate           2-1/2 grains. 
Morphia                         1-1/2   "
Aqua destil                     1-1/2 drams.

As a diagnostic this mixture of the two is said to be far superior to either cocaine or morphia alone.

In connection with this subject, Professor Hobday has published, among others, the following cases illustrating the practical value of this method of diagnosis:[A]

[Footnote A:  The Journal of Comparative Pathology and Therapeutics vol. viii., pp. 27, 43.]

CASE I.—­Cab gelding.  Seat of lameness somewhat obscure; navicular disease suspected.  Injected 2 grains of cocaine in aqueous solution on either side of the limb, immediately over the metacarpal nerves.

Five Minutes.—­Lameness perceptibly diminished.

Ten Minutes.—­Lameness scarcely perceptible.

CASE II.—­Mare.  Obscure lameness; foot suspected.  Injected 30 minims of a 5 per cent. solution on either side of the leg just above the fetlock.

Ten Minutes.—­No lameness, thus proving that the seat of lameness was below the point of injection.

CASE III.—­Cab gelding, aged, free clinique; Messrs. Elme’s and Moffat’s case.  Obscure lameness; foot suspected of navicular disease; very lame.  Injected 30 minims of a 5 per cent. solution of cocaine on either side of the leg over the metacarpal nerves.

Six Minutes.—­Lameness perceptibly less; there was no response whatever on the inside of the leg to the prick of a pin.  On the outside, which had not been injected so thoroughly, there was sensation, although not so much as in a healthy foot.

Ten Minutes.—­Lameness had almost disappeared; so much so, that the opinion as to navicular disease was confirmed, and neurectomy was performed.  Immediately after this operation there was no lameness whatever.

The same author also reports numerous cases among horses and cattle, dogs and cats, pointing out the toxic properties of the drug.  The symptoms following an overdose are interesting enough to relate here, and I select the following case of Professor Hobday’s as being fairly typical:[A]