Neurectomies have been performed and recoveries following were attributed thereto; fascial divisions in the crural region have been done with good results and this manner of treatment has its favorers.  Advocates of tenotomies, likewise, are to be found.  Consequently, one may summarize thus:  Spring-halt is a disease of unknown origin—­the exact cause has not been determined; therefore, all treatment is, in a way, experimental.  The recommendation of any given procedure in handling cases must then be a matter of opinion based either upon practical experience or knowledge of the experiences of others.  Divisions of the lateral digital extensor (peroneus) below the tarsus near its point of insertion to the extensor of the digit is recommended here because it is followed by a percentage of recoveries that is as large as in any other method of treatment and the operation is not difficult to perform nor is its performance fraught with any dangerous complications.  In selected subjects about fifty per cent of cases recover in from two to six weeks following this operation.

[Illustration:  Fig. 53—­Lateral (external) view of tarsus showing effects of generalized tarsitis.]

Open Tarsal Joint.

Like the tibia the hock is exposed to frequent injuries and in some cases wounds perforate the joint capsule.  When due to calk wounds where horses are kicked, the injury is often on the side of the tarsus (medial or lateral) and such wounds not infrequently result in infectious arthritis.  Horses sometimes jump over wire fences and wounds are inflicted which constitute extensive laceration of the joint capsule.  In firing for bone spavin, where a deep puncture is made very near the tibial tarsal (tibioastragular) joint if infection gains entrance, serious and generalized infection of the open joint cavity supervenes in some cases.

Symptomatology.—­There is no marked difference in the constitutional disturbances which are occasioned in this condition and those encountered in other cases of septic arthritis (previously considered herein) except that there is a difference in the degree of resultant derangement and local tissue changes.  Chiefly, because of the difficulty encountered in keeping the hock joint in an aseptic condition or securely bandaged, open tarsal joint constitutes a more serious condition than a similar affection of the fetlock.  Otherwise, a very similar condition obtains and the same diagnostic principles serve here that have been described on page 110 in considering open fetlock joint.

Treatment.—­The same plan that is described in detail for treatment of similar conditions affecting the fetlock joint is indicated in this affection.  Exceeding care must be exercised in bandaging the hock, however, lest the animal be so irritated that in the extreme flexion of the tarsus which is often caused by bandaging, the wound dressings may be completely deranged.  A wide gauze bandage material is most