Aortic Thromboembolism (ATE) in Cats


Overview of Aortic Thromboembolism (ATE) in Cats

Aortic thromboembolism, also referred to as saddle thrombus, is a common complication associated with all types of heart disease in the cat. A thrombosis is the formation of a blood clot. An embolism is when the clot lodges within a vessel. It is thought that clots form in one chamber of the left side of the diseased heart. Eventually, these clots break free and travel in the blood vessels until they become lodged or stuck.

Below is an overview of Aortic Thromboembolism in cats followed by detailed information about the diagnosis and treatment of this serious condition. 

The most common site for the clot to lodge is in the far part of the aorta, in the area between the rear legs. This cuts off the blood supply to both rear legs. A clot can also get stuck in the artery that supplies the front legs, kidneys or intestines or can clog an artery to the brain. Clots rarely lodge in veins since the right side of the heart is not commonly involved.

When a clot lodges, the cat can no longer use his rear legs and drags them. The cat usually becomes painful and begins crying. The rear feet are often cold to the touch and the pads of the feet blue in color, due to a lack of blood flow.

The vast majority of cats with saddle thrombus also have underlying heart disease that may not be apparent. Unfortunately, the stress and anxiety of the embolism may precipitate congestive heart failure.

What to Watch For

  • Sudden onset of dragging rear legs
  • Difficulty breathing
  • Crying
  • Panting or open mouth breathing
  • Diagnosis of Aortic Thromboembolism in Cats

    Most cases of saddle thrombus are diagnosed based on the history and physical exam findings. A lack of pulses to the rear legs, cold paws and blue tinged footpads are highly suspicious of saddle thrombus. Other tests may be performed to determine if underlying heart disease is present and the severity.

  • Complete blood count
  • Biochemical profile
  • Chest X-rays
  • Ultrasound of the heart
  • Treatment of Aortic Thromboembolism (ATE) in Cats

    Treatment will vary depending on the severity and location of the clot and the severity of the underlying heart disease.

    Congestive heart failure is treated with:

  • Oxygen
  • Diuretics for fluid accumulation within the lungs
  • Heart medication
  • Nitroglycerine

    Sometimes, medication is used to treat the clot. This may include:

  • Pain medication
  • Blood thinners
  • Aspirin
  • Home Care and Prevention

    There is no home care for saddle thrombus. If you suspect your cat has saddle thrombus, he should be examined by your veterinarian immediately. Over 90 percent of cats with saddle thrombus also have underlying heart disease that often requires treatment.

    Cats with known heart disease may be placed on aspirin therapy in an attempt to reduce the risk of developing saddle thrombus.

    In-depth Information on Aortic Thromboembolism (ATE) in Cats

    Aortic thromboembolism (saddle thrombus) is a relatively common complication associated with heart disease. The most common heart disease in cats is hypertrophic cardiomyopathy. The walls of the diseased heart allow the formation of clots in the left atrium, the upper chamber of the heart. These clots then become dislodged and travel down the aorta, the main vessel leaving the heart. Clots most often become lodged at the base of the aorta when it divides into the arteries that supply blood to the rear legs. This causes a sudden onset of inability to use the rear legs, dragging the rear legs and cold paws. Cats often howl and cry in pain.

    Clots may also lodge anywhere in the body including the arteries to the kidneys, intestines, front arms or brain. If affecting the front arms, usually the right front arm is affected.

    After the clot lodges in the vessel, it almost always dissolves on its own over time, although it may cause severe nerve and muscle damage. This damage may not be reversible. For this reason, it is recommended that your cat receive immediate treatment for saddle thrombus.

    Following treatment, about 35 to 40 percent of cats are able to walk again, usually within three weeks of the episode. Unfortunately, a significant number of cats do not survive the heart failure that often accompanies saddle thrombus. Other cats may not survive the muscle and nerve damage that occurrs with the clot.

    Cats that do survive an episode of saddle thrombus unfortunately have a 90 percent chance of recurrence within six months.

    Other diseases may cause sudden onset of dragging rear legs. These include:

  • Intervertebral disk disease
  • Tumor of the spinal cord
  • Pelvic fracture
  • Traumatic injury
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