A long heavy sterile needle, which is connected with an oxygen tank by means of six feet of rubber tubing, is thrust into the depths of the affected muscles and the gas is gently introduced into the tissues.  One needs exercise extreme care that the gas enter slowly because great pain is produced by the sudden injection of the oxygen.  Likewise too much of the gas must not be introduced at one place.  When the oxygen is slowly introduced it may be allowed to enter the tissues until the subject gives evidence of experiencing considerable pain, or if the parts are not particularly sensitive, a reasonable amount (enough to cause a mild degree of diffuse inflammation) is introduced at each one of five or six points.  In large animals more points of injection may be used.

No infection or other bad results will follow the execution of a good technic and the treatment may be repeated every three or four weeks until either marked regeneration of tissue is evident or the case is obviously proved hopeless.

Paralysis of the Obturator Nerve.

Anatomy.—­The obturator nerve, situated at first under the peritoneum, accompanies the obturator artery through the obturator foramen and gaining the muscles on the internal face of the thigh, terminates in the obturator externus, adductors, pectineus and gracilis, also giving twigs to the obturator internus (Strangeways).

Etiology and Occurrence.—­This condition occurs upon rare occasions as the result of injury such as falls which cause extreme abduction of the legs, or in pelvic fracture where the nerve is directly injured, or when melanotic tumors or other new growths compress the nerve in such manner that its function is suspended.  Paralysis of the obturator nerve or nerves is met with rather frequently, notwithstanding, in mares, following dystocia.  The nerves (one or both) may become bruised at the brim of the obturator foramen by being caught between the pelvis and the body of the fetus in some cases of protracted labor.

Symptomatology.—­In a unilateral affection there may be little evidence of the trouble while the subject is standing; or there is to be seen some abduction; or the affected member may present abduction of the stifle and stand “toe outward.”  If the animal is walked there will be manifested more or less abduction and the character of the impediment varies according to the nature of the involvement.

Following protracted cases of labor in some instances where only a unilateral paralysis exists, walking is performed with difficulty; the subject may be unable to support weight with the affected member and is obliged to hop on the one sound hind leg.  In bilateral affections, they are unable to rise.  If the condition is severe the sling is required to keep the subject standing, and with this care, recovery will follow.

Treatment.—­If new growths or callosities or similar conditions affect the nerve, little, if any, hope for recovery exists.  In young and vigorous subjects where cause is not definitely known, a course of strychnin may be given.  Good nursing, providing for the subject’s comfort and allowing moderate exercise, constitute rational treatment.  Stimulating embrocations on the abductor muscles resorted to in cases during the incipient stage may prove helpful.