THROMBOSIS OF POSTERIOR AORTA AND ITS BRANCHES. 
679 
Thrombosis of the external iliac artery, which supplies the glutei and 
quadriceps femoris, produces a “ supporting leg lameness,” which closely 
simulates crural paralysis. The animal is unable to stand on the limb, 
because at every attempt the joints become flexed. Paralysis of the 
glutei is followed by loss of balancing power, and when double-sided 
by rolling to and fro of the hindquarters. In obstruction of the caudal 
arteries the tail hangs limply. Horses with double-sided iliac thrombosis 
rapidly lose control of both hindquarters when galloped. The hind 
limbs approach one another more and more closely, the hoofs are planted 
on the ground just alongside of one another, and finally the animal 
comes to the ground with the hindquarters first. 
A rare condition was described by Haas. When first examined the horse 
showed symptoms of thrombosis of the left iliac artery. Fifteen minutes 
later, when again moved, the lameness seemed transferred to the right limb. 
On post-mortem examination there was found extending into the left iliac 
artery a thrombus, which, however, could easily be carried by the blood-stream 
into the right. Haas saw thrombosis of the posterior aorta in a cow. Strebel 
saw a cow which was only capable of standing for a few moments at a time. 
On post-mortem the cause was found to be thrombosis of the left iliac artery. 
In bilateral thrombosis, or in thrombosis of the aorta, these symptoms 
are combined, and may become so severe that the animal is unable to 
support the hindquarters, even when at rest. Such cases often show 
dyspnoea, tumultuous action of the heart, cramp in the muscles of the 
hindquarters, and, if the animals be worked, epileptiform convulsions of 
the entire body. Though the rest of the body is bathed in perspiration, 
the affected region remains dry and cold. Sometimes even during rest 
the limb seems colder than its neighbour. 
Stallions are sometimes unable to copulate. Holier saw one in which 
erections occurred, but were not followed by ejaculation of semen. The 
post-mortem of such animals shows emphysema of the lung, with 
hypertrophy and dilatation of the heart. 
According to Terrillon’s observations on men suffering from this 
disease, the attack is accompanied by a feeling of painful stiffness and 
severe burning. In recent cases, animals evince pain by lifting the limb 
when standing at rest; soon after, lameness becomes apparent. Holler 
once saw the primary attack of embolism. The symptoms were severe 
dyspnoea, laboured action of the heart, frequent pulse, and cramp in the 
affected muscles. 
The prognosis depends on the degree of interference with movement, 
but the tendency is always towards aggravation of symptoms, not towards 
improvement, and only in slight cases can the development of an efficient 
collateral supply and recovery be looked for. Of eleven army horses 
affected during the year 1891 with thrombosis of the aorta, of its 
branches, or of the radial artery, only one recovered. 
