portion of the articular surface of the
femur. The internal trochanter was also fractured in four small pieces.
In this case it is fair to suppose that the mule in trying to regain
footing on a slippery floor violently abducted the legs and fracture
resulted. It is possible also that a temporary luxation of the patella
took place first and caused the animal to struggle in such manner that
fracture followed.

[Illustration: Fig. 46--Oblique fracture of the femur of a 1,500
six-year-old draft horse. Showing shortening of bone, owing to a lateral
approximation of the diaphysis because of muscular contraction. Photo by
Dr. Edward Merillat.]

Symptomatology.--According to Cadiot and Almy,[40] "regardless of the
location of femoral fractures, the subject is usually intensely lame,
the animal frequently walking on three legs--fractures of the diaphysis
are characterized by an abnormal mobility."

As a rule, crepitation is to be recognized in fractures of the shaft of
the bone, by passively moving the leg to and from the medial plane
(adduction and abduction).

Fracture of the trochanter major is signalized by local swelling and
evidence of pain; the forward stride is shortened because this movement
tenses the tendon of the gluteus major (maximus) which is attached
principally to the trochanter.

[Illustration: Fig. 47--Same bone as in Fig. 46 after about six months'
treatment. In this case Dr. Merillat employed a weight to counteract
muscular contraction. It is noticeable that very little provisional
callus has formed in this case, and in spite of unusual ingenuity and
good facilities for caring for the subject, union of bone did not
occur.]

Treatment.--Reduction of femoral fracture in the horse is practically
impossible, and retaining the broken bones in coaptation is not possible
by means of mechanical appliances. Consequently, prognosis is
unfavorable in fracture of the body of the femur. When union of bone
occurs, there results shortening of the leg and animals are rendered
permanently lame. If the immediate region of the head of the bone is
involved as well as in case of fracture of the condyles, an incurable
arthritis ensues.

Where the trochanters are broken, chronic lameness and muscular atrophy
is the result. Therefore, it is evident that, because of the manner of
function of the femur, the leverage afforded by its great trochanter and
its heavy muscular attachments, fractures of this bone in the horse do
n