of the coracoradialis (biceps brachii), while the metacarpus and phalanges are bent by the action of the posterior antibrachial muscles.  The knee is carried in advance, level with, or in front of, a vertical line dropped from the point of the shoulder.  The hoof is usually rested on the toe, but when advanced beyond the above mentioned vertical line, it may be placed flat on the ground, the joints then being less markedly bent.  When the limb as a whole is flexed, it may be brought into normal position by thrusting back the knee with sufficient force to counteract the action of the flexor muscles.

[Illustration:  Fig. 9—­Merillat’s method of fixing carpus in radial paralysis.  Courtesy, Alex.  Eger.]

When made to walk, the animal being unable to exert muscular action with the paralyzed structures, limply carries the member as a whole, and there is shortening of the anterior portion of the stride.  There being loss of function of the triceps brachii, it is impossible for the subject to straighten the leg in the normal position for supporting weight; therefore, any attempt to bear weight results in further flexion of the affected member and the animal will fall if the body is not suddenly caught up with the sound leg.

Differential Diagnosis.—­In making examination of these cases, one can exclude fracture by absence of crepitation and usually, also, swelling is absent in radial paralysis.  In a typical case of radial paralysis, the affected leg can sustain its normal share of weight if placed in position, that is, if the carpal joint is extended in such manner that the leg is positioned as in its normal weight-bearing attitude.  In brachial paralysis, whether due to fracture of the first rib or to other serious injury, it is impossible for the subject to support weight with the affected member even when it is passively placed in position.

No difficulty is ordinarily experienced in differentiating radial paralysis from muscular injuries to the triceps; yet, in some cases of “dropped elbow,” it is necessary to observe the progress of the case for ten days or two weeks before one can positively establish a diagnosis.

Quoting Merillat[12]:  “When, after four weeks, there is no amelioration of the paralysis, the muscles have atrophied, and the patient has become emaciated from pain and discomfort, the diagnosis of brachial paralysis with fracture of the first rib may then be announced.”

Prognosis.—­When no complete paralysis of the brachial plexus or no fracture of the first rib exists, the majority of cases recover completely in from ten days to six weeks.  Some writers claim that recoveries occur in ninety per cent of cases when conditions are favorable.

Treatment.—­When incomplete radial paralysis exists, little needs be done except to allow the subject moderate exercise and to provide for its comfort.  Local applications, stimulative in character, are beneficial, and the internal administration of strychnin is indicated.