What are Aortoiliac Thrombosis?
Aortoiliac thrombosis is a disease of the vascular system which is progressive. The disease is described as progressive with lameness of the hind legs connected with a blood clot in the terminal aorta. This blood clot, or thrombus, reduces or blocks the flow of blood. This is typically brought on by exercise; however, research continues to be conducted on the specific cause of the disease. This condition is also referred to as aortic-iliac thrombosis. The rate of occurrence of this condition is in approximately 1.5% of racing thoroughbreds.
The terminal aorta is the main artery that comes from the left ventricle. It is the main area that basically controls the arterial system. The terminal aorta includes the ascending aorta, the thoracic aorta, the abdominal aorta, and the aortic arch. All of these divisions of the main aorta are crucial to the functionality of the heart and the arteries.
Aortoiliac thrombosis in horses occurs when the terminal aorta of the hind area of the horse develops a clot, or thrombus.
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Symptoms of Aortoiliac Thrombosis in Horses
Symptoms of this rare disorder are very specific. If your horse is suffering from any of the following symptoms, make an appointment with your veterinarian. Symptoms may include:
- Hind-end lameness after exercising
- Cool limbs
- Lack of sweating during exercise
- Low pulse
There are several other conditions that exhibit similar symptoms to Aortoiliac thrombosis. Your veterinarian will perform a variety of tests and pay close attention to your horse’s symptoms to rule out any other conditions. Types of differential diagnoses can include:
- Cervical vertebral malformation
- Musculoskeletal lameness
- Trauma in pelvis or spinal areas
- Back disorders
- Myopathy from postexercise
Causes of Aortoiliac Thrombosis in Horses
Aortoiliac thrombosis is still being researched in horses, and may be caused by a variety of factors, such as a possibility of genetic predisposition and a light-weighted horse. Causes may include:
- Trauma of the arterial endothelium, causing formation of plaque
- Degenerative vascular disease
- Bacterial infections
- Parturition causing direct trauma
- Migrating types of Strongylus vulgaris, or blood worms, within the arterial walls
Diagnosis of Aortoiliac Thrombosis in Horses
If your horse is having the above symptoms, make an appointment with your veterinarian. Your veterinarian will immediately assess your horse’s symptoms and will need to gather information from you. The information your veterinarian will need to know will include your horse’s symptoms and when they occurred, if your horse exercises and has symptoms after exercising, among other behavioral and systematic changes.
The veterinarian will do a thorough examination of his hind limbs. He may also take blood work, a biochemistry profile, and any other laboratory testing that he feels are necessary, such as a test for serum and muscle enzyme levels. These tests will be conducted before he exercises, and then after. He will be looking for an increase in creatine kinase to aid him in his diagnosis. A rectal ultrasound may be ordered so the veterinarian can take a closer look at his arteries, both before and after a session of exercise. He will look for weakness around the pelvic area and within the pelvic limbs, any ataxia, and hesitance to put the hind leg or legs down after exercise, or any cow-kicking after an exercise session. He will also check to see if the affected limb is sweating and a reduced temperature in the affected leg, even though the other parts of the horse may be perspiring. A low pulse rate may also be a cause for concern.
The medical professional may palpate the rectum and observe an area of hardness, or feel firmness in an area, and this could signify largeness in the arteries. A test known as nuclear angiography may reveal a reduction of the flow of blood through the specific iliac artery or arteries, which will give the veterinarian a great deal of information.
Treatment of Aortoiliac Thrombosis in Horses
Unfortunately, there are no specific medications that will rid your horse of a thrombus. Therapies may be effective, depending on the severity of your horse’s condition. Treatment may include:
Anti-inflammatory drugs and pain relievers may help your horse with any discomfort he is having due to the condition. Your veterinarian may recommend platelet inhibitors, which decrease the aggregation of platelet and reduce the formation of thrombus. He may also prescribe fibrinolytic agents, anthelmintics, and anticoagulant medications.
Removal of the thrombus, known as intraluminal arterial thrombectomy may improve your horse’s overall health. This may or may not be suggested by your veterinarian, as each thrombosis will have a very high chance of recurrence.
Therapeutic treatment for this condition may be recommended to give your horse pain relief, improve his collateral circulation, aid in thrombolysis, and to prevent the formation of additional thrombosis. Your veterinarian will explain to you the various therapeutic treatment options.
Recovery of Aortoiliac Thrombosis in Horses
In cases where both sides of the hind end are affected, the prognosis is guarded, at least. If your horse has responded to treatment methods, his chances for recovery are much better. Your veterinarian will be closely involved in the treatment of your horse and will monitor his recovery.
Your veterinarian will give you advice and instructions on how to care for your horse at home, including how to administer any medications you may need to give and how often.