Aortic thromboembolism is extremely painful for cats, so you will most likely hear screeching and notice the cats has lost control if its legs. The symptoms will begin suddenly and take you and your cat by surprise, but you must be ready to act quickly. If you spot any of these symptoms, take your cat to a veterinarian immediately.

Aortic thromboembolism, also known as “saddle thrombus,” occurs when a blood clot cuts off the blood supply to the cat’s hind legs, leaving his two back limbs paralyzed. This condition is usually a complication of heart disease or hypertrophic cardiomyopathy, although other health conditions may contribute to it as well.

Aortic thromboembolism symptoms will come on suddenly and without warning. As soon as you spot these symptoms, it’s imperative you bring your cat to a veterinarian right away for emergency treatment. Some of the symptoms you should look for include:

Aortic thromboembolism occurs when a blood clot in the heart breaks free and begins to travel downstream, where it becomes lodged at the base of the aorta. The blockage prevents blood from traveling into the hind legs, so the cat will immediately begin to experience pain. 

Clots form in cats that are already suffering from heart disease or hypertrophic cardiomyopathy, which is an enlarged heart. Other conditions, such as hyperthyroidism and lung cancer, can also contribute to blood clot formation. Cats that have any of these pre-existing health problems are at risk of suffering from aortic thromboembolism.

Take your cat to a veterinarian as soon as you spot these symptoms of aortic thromboembolism. Tell the vet what symptoms you have observed and if your cat has any pre-existing health conditions that could contribute to blood clot formation. 

The vet should be able to make a diagnosis based solely on the cat’s behavior and condition of the back legs, however, some tests will be run to confirm the diagnosis. First, a complete blood count and biochemistry profile will be performed. These tests will give the vet a better picture of how the organs are functioning, and whether anemia or bacterial infections could be a factor. 

Because aortic thromboembolisms mainly occur as a consequence of heart disease or hypertrophic cardiomyopathy, the vet may want to conduct tests on the cat’s heart. An echocardiogram, which is an ultrasound of the heart, may be performed to determine whether your cat has either one of these conditions, while a chest X-ray is used to look at the overall size and health of the heart. Vets may suggest a Doppler ultrasound as well, to confirm there is no blood flowing through the legs.

Surgery may need to be done as soon as possible to remove the existing blood clot and allow blood to flow to the hind legs, however this is usually only recommended in extreme cases. Vets usually prefer to treat aortic thromboembolism with “clot buster” medications and blood thinners to prevent further clots.

Your cat will most likely receive IV fluids to prevent dehydration and help him recover from his initial shock. If the cat is panting heavily or struggling to breathe, the vet may place an oxygen mask on him to help him calm down and regain his strength. Because blood clots are very painful for cats, a vet may also administer strong pain medication to keep the cat comfortable. Vets may ask to keep your cat for up to 48 hours to administer medication and closely monitor his condition.

However, many cat owners elect to have their pets euthanized because of the low survival rate associated with aortic thromboembolism. This is never an easy decision to make, so talk with your vet about what the best choice is for your cat. 

It is never a guarantee that your cat will recover after experiencing an aortic thromboembolism. Even if the blood clot is successfully removed or treated with medication, the cat will still suffer from the underlying condition, usually heart disease or hypertrophic cardiomyopathy. Some cats may never have another blood clot again, although is rare. Many cats that survive the first blockage will experience another episode within the next year. 

The outlook is slightly better for cats who were not completely paralyzed in both legs as a result of the blockage. If your cat was only partially paralyzed, or if the blockage only affected one leg, he may recover mobility in his legs over time. While he recovers, you will have to keep him immobile in a cage and monitor him closely to ensure he is comfortable.