352 VETERINARY SURGICAL THERAPEUTICS. 
to reduce fractures and dislocations. Embolics may also soften arteriay 
coats and promote rupture (Cadéac). In the great majority of cases, 
alteration of the vascular walls (atheroma, aneurisms) has been ob. 
served on a level with the rupture. Some cases, however, prove the possi- 
bility of rupture of vessels whose walls present no lesion of degener- 
_ ation. When it occurs in a superficial artery, a diffuse, warm tumor fotms 
at once, irregular and pulsating as aneurisms do, though not so powerfully ; 
seldom can the bellow murmur be detected in them. . This bloody effu- 
- sion, called diffused or false aneurism, is not an aneurism. The name of 
. diffuse aneurismal hematoma, proposed by Michaux, is to be preferred. 
The large arteries of the thorax and abdomen rupture more frequently, 
than superficial vessels. Sometimes it is the pulmonary artery (Hering, 
Hartmann, Prietsch). At the post-mortem of a dog, that had died sud- 
denly, we found a large distension of the pericardium by blood ex- 
travasated through two little tears situated on the right face of the pulmonary 
_artery. In the zone where the tears were, the artéry was very thin and 
presented several small transparent spots. But, no doubt, it is the aorta 
which is injured in the greater number of cases. Larcher has reported 
twelve observations at the Société Centrale de Médecine Vétérinaire (1876). 
In all, the tears had taken place at the base of the primitive aorta, at a point 
where the vessel is still covered by the pericardium ; this contained a notice- 
able quantity of blood, sometimes fluid, more generally coagulated. In five 
cases the structure of the vessel was the seat of atheromatous degeneration ; 
in two, no visible alteration could be detected ; in five others, no mention is 
made of the condition. To these twelve observations of Larcher, we 
might add those of Vatel, Maillet, Rigollat, Palat and others published in 
- other countries or recorded by us at the Alfort clinics. In horses, rupture 
of the aorta is not rare. 
If, generally; the diagnosis is only positive at the time of post-mortem, 
the accident can be suspected, taking into consideration the circumstances 
in which it takes place and the symptoms it gives rise to. The symptoms 
are those of large internal hemorrhages. “In one case, a high jumper, 
after a prodigious jump, suddenly drops on his hind quarters, to rise no 
more. In another, the horse, as he is cast on the bed to be submitted to 
an operation, makes a powerful inspiration, his eyes roll in their orbits, the 
respiration and beatings of the heart stop and immediately he is pulseless.” 
(Larcher). In two cases that we have seen, the rupture took place during 
the struggling of the animal while lying on a bed for operation. The 
aorta may give way at a point some distance from the heart. At the autopsy 
of a twelve year old mare, that died suddenly in stocks, we have found a 
rupture of the aorta on its superior face, on a level with a small exostosis 
of the third lumbar vertebre. The vessel had two ulcerations; the 
