Aorto-iliac thrombosis

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Aorto-iliac Thrombosis

Aorto-iliac thrombosis (AIT) is a progressive vascular disease which causes blockage of the blood vessels to the hindlimbs of the horse. The disease is characterized by hindlimb lameness following exercise that may also remain cool when the horse is sweating.

Horses may demonstrate severe discomfort during or after exercise by pawing and showing colic-like symptoms. These symptoms tend to pass within an hour. Horses that are forced to work through the pain develop a more severe lameness and may require significantly more time for the clinical signs to resolve.

Early treatment is essential. As the thrombus increases in size, reduced performance occurs progressively with less strenuous activity.


Increasing poor performance
Hindlimb lameness during or following exercise
Weak or absence of digital pulse
Altered behavior
Cold extremities despite sweating elsewhere
Colic-like symptoms


  • History
  • Clinical signs
  • Physical exam
  • Ultrasonography - used to recognise the thrombus in the aorta, internal and external iliac artery
  • Thermography
  • Nuclear scintigraphy



Anticoagulant agents
Surgical thrombectomy - In a study of 17 horses which had the surgery, 65% of the horses regained their athletic performance and 53% of the operated horses performed at their previous level.
Daily administration of aspirin


  • Regular veterinary exam
  • Regular deworming to control parasites


Guarded for return to previous levels of athletic performance

Scientific Research

General Overviews