Etiology and Occurrence.—­Pelvic fractures are usually caused by falls or other manner of contusion.  Cases are reported where it would seem that fracture of the iliac angle resulted from muscular contraction, but it is certain that most fractures of this kind are due to collisions with door jambs or similar injuries.  In old horses especially, fracture of pelvic bones occurs frequently.  This form of injury is of more frequent occurrence in animals of all ages that work on paved streets.  The country horse is not subjected to the uncertain footing of the slippery pavement, nor to injuries which compare with those caused by contusions sustained in falling upon asphalt or cobble-stones.

Symptomatology.—­While in many cases of pelvic fracture lameness or abnormal decumbency are the salient manifestations, yet the pathognomic symptoms are crepitation or palpable evidence which may be obtained by rectal or vaginal examination.  In fractures of the angle of the ilium and the ischial tuberosity, perceptible evidence always exists.

In cases where fracture of some portion of the pelvic girdle is suspected and the subject is able to walk, crepitation is sought by placing one hand on an external angle of the ilium and the other on the ischial tuberosity and the animal is then made to walk.  Or, by placing the hands as just directed, an assistant may grasp the horse’s tail and by alternately exerting traction on the tail and pushing against the hip in such manner that weight is shifted from one leg to the other, crepitation may be detected.

Fracture of the pubis near its symphysis constitutes a grave injury, as there is danger of the bladder becoming caught in the fissure and perforation of its wall may result.  Such a case is reported by Bauman[36] wherein a three-year-old gelding bore the history of having been lame for ten days.  Upon rectal examination the bladder was found to be hard and tumor-like and about the size of a baseball.  The body of the ischium in this case was fractured and a rent in the bladder was caused by a sharp projecting piece of bone.  Autopsy revealed, in addition to the fracture and rent of the bladder wall, a large quantity of urine in the peritoneal cavity.

In other instances hemorrhage caused death and not infrequently infection was responsible for a fatal issue.  Moller,[37] quoting Nocard, describes a case where fracture occurred through the region of the foramen ovale and paralysis of the obturator nerve followed.

Fractures which include the acetabular bones cause great pain.  This is manifested by marked lameness, both during weight bearing and when the member is swung.  Such cases terminate unfavorably—­complete recovery is impossible.

Where small portions of the angle of the ilium are broken, and the skin is left intact, there exists the least troublesome class of pelvic fracture.  If large portions of the ilium are fractured, considerable disturbance results.  There eventually occurs more or less displacement in such cases, if such displacement does not take place at the time of injury.  The same may be said of fracture of the tuber ischii, but when these bones are fractured a more serious condition results.