If you have a cat, knowing and being able to recognize the symptoms of a thrown blood clot can potentially make the difference between life and death for your cat. This guide will explain how an aortic thromboembolism can develop, what symptoms you should look out for, and what treatment options there are.


Aortic thromboembolism is the development of a blood clot in the left atrium of a cat's heart. A blood clot can develop due to fat particles or bacteria building up and blocking the artery. When it's located in the left atrium, a portion of the blood clot can break free and migrate through the cat's arteries,  eventually lodging itself in the arteries that supply blood to the cat's hindquarters. If the clot remains intact, only one leg is affected, but if it splits into two or more parts, it may block blood flow to both legs.


Once a blood clot has reached the cat's hindquarters, the cat will likely experience these symptoms:

  • Rear Paralysis - Depending on whether the clot was intact or broke into multiple parts, one or both of the rear legs and the tail may suddenly become paralyzed. The cat may be able to walk, but will drag one or both of its rear legs.
  • Kidney Failure - Blood supply to the kidneys may be stopped, or the cat may be unable to urinate. If the bladder can't empty, the kidneys will stop functioning, and this will cause a rapid buildup of toxins in the blood.
  • Blue Paws - Pads and toenails may appear bluish, indicating a lack of blood supply.


Unfortunately, few treatments for aortic thromboembolism exist for cats so far. A veterinarian at a place like Denville Animal Hospital will attempt to thin the blood clots so that blood flow to the legs can begin again. Anticoagulants like heparin can be helpful in thinning blood clots in cats, and if it's successful, the veterinarian may prescribe clopidogrel to help prevent new blood clots. In addition, the cat may need physical therapy to regain use of its rear legs.

If the arteries can't be cleared and only the rear legs are affected, amputation may be an option to remove the dying or dead tissue. Losing a limb or limbs is a trauma that a cat will need to adjust to, but one survey showed that 90% of owners of amputee cats believe that their cats have a normal quality of life.

Getting your cat to your veterinarian or an emergency animal hospital immediately after symptoms develop increases the survivability of this condition, so if you ever see these signs, don't delay.