FRACTURES OF THE PELVIS. 735 



(3) Deformity of the quarter is, as a rule, best marked in fractures 

 of the ilium. In fracture of the outer angle, the loose piece of bone 

 is drawn forwards and downwards by the oblique abdominal muscle, 

 and by the tensor vaginae femoris and lies towards the abdominal 

 wall, so that the outer iliac angle seems to have disappeared. To 

 detect this, the animal is placed with the hind-feet level, and the 

 observer standing behind, compares the relative contours of the 

 outer iliac angles. The larger the broken portion, the more marked, 

 of course, will be the asymmetry. 



In fractures of the shaft of the ilium, the entire ilium, and 

 especially its outer angle, sinks ; this symptom can almost invariably 

 be detected if the horse be made to stand equally on both feet. 



A peculiar change in form follows fracture of the external branch 

 of the ischium ; the buttock is flattened at the height of the tuber 

 ischii, whilst the region of the hip-joint appears considerably swollen, 

 and the ilium slightly depressed. The abnormality is discovered 

 by standing a few steps behind the animal and regarding the pelvis. 

 Fractures through the acetabulum or os pubis are not generally 

 followed by changes of form in the quarters, though in fracture of 

 the acetabulum a depression may sometimes be seen over the 

 hip-joint. 



(4) The bones of the pelvis are seldom abnormally mobile, except 

 when the external and internal angles of the ilium are simultaneously 

 fractured, though in exceptional cases mobility is present after 

 fracture of the shaft and body of the ilium, or of the ischial shaft. 

 In such cases the outer angle of the ilium yields when pressed on, 

 and crepitus may sometimes be detected. 



(5) In fractures of the pubis, cedematous swelling sometimes 

 occurs under the belly in the region of the udder or scrotum, but 

 its absence does not exclude the possibility of such fractures. 

 Fractures of the os pubis are often followed by swelling about the 

 vagina ; fragments of the pubis or ischium may penetrate the 

 vagina and produce bleeding from the vulva. After fractures of 

 the tuber ischii, swelling may also occur in the neighbouring thigh 

 muscles. On the other hand, in fractures of the ilium, excepting 

 the outer angle, swelling is seldom externally visible, but can be 

 discovered by rectal examination. 



(6) Unusual mobility of the thigh. All fractures which divide the 

 pelvic girdle behind the cotyloid cavity, as well as fractures into 

 the acetabulum, with relaxation of the ligament um teres, are 

 characterised by abnormal freedom in abduction, sometimes also 

 in adduction, of the thigh of the affected side. 



