Feline arterial thromboembolism
Also known as Saddle thrombus, Aortic thromboembolism.
A clot formed in a diseased heart breaks loose and blocks the artery that carries blood to the back legs. The cat is suddenly paralysed and in great pain.
If your cat suddenly drags its back legs and cries out in pain, go to an emergency vet now.
- System
- Heart and circulation
- Is it urgent?
- Usually
- Spreads to other cats
- No
- Spreads to people
- No
- Typical cost in Spain
- Emergency care and hospitalisation, €800–2,500.
Symptoms
- Sudden paralysis of one or both back legs
- Crying out in severe pain
- Cold legs and pale or bluish paw pads
- Fast breathing
- Sometimes affects a front leg
Causes
Almost always heart disease, especially hypertrophic cardiomyopathy, which has often not been diagnosed.
How it is diagnosed
Examination (absent pulse, cold legs), echocardiography and comparing glucose or lactate between legs.
Treatment
Strong pain relief, oxygen, anti-clotting drugs and treatment of heart failure. It is a very hard situation, and euthanasia is an option to discuss with the vet.
No doses, on purpose: any medicine must be prescribed by your vet for your cat.
Prognosis
Guarded. Some cats regain mobility within weeks, but the risk of it happening again is high.
Prevention
Diagnose heart disease in time and give the anti-clotting medicine as prescribed.
Breeds at higher risk
It is described more often in these breeds. That does not mean all of their cats will have it, nor that a moggy is free of it.
Frequently asked questions
What causes feline arterial thromboembolism?
Almost always heart disease, especially hypertrophic cardiomyopathy, which has often not been diagnosed.
Can feline arterial thromboembolism be cured?
Guarded. Some cats regain mobility within weeks, but the risk of it happening again is high. Strong pain relief, oxygen, anti-clotting drugs and treatment of heart failure. It is a very hard situation, and euthanasia is an option to discuss with the vet.
How much does it cost to treat feline arterial thromboembolism?
As a guide for Spain in 2026: Emergency care and hospitalisation, €800–2,500. Prices vary a lot between clinics and cities, and out-of-hours emergencies cost more.
Which breeds are most at risk?
It is described more often in Maine Coon, Ragdoll, British Shorthair and Sphynx. That does not mean every cat of those breeds will have it, nor that a moggy is free of it.
More in heart and circulation
Educational content from Michipedia. It does not replace diagnosis or treatment by a vet: if you have any doubt about your cat's health, ask. Costs are a guide for Spain in 2026.