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.

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

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

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.