Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Sudden paralysis in a cat is an emergency. The most common cause of sudden back-leg paralysis in cats is aortic thromboembolism (“saddle thrombus”), a blood clot that blocks blood flow to the back legs, usually caused by underlying heart disease. Signs include crying in pain, cold back legs, and pale or bluish paw pads. Other causes include trauma, spinal tumors, and infections. Go to an emergency vet immediately.
Signs of a saddle thrombus
- Sudden inability to use one or both back legs
- Crying or yowling in pain
- Cold back legs and paws
- Pale, gray, or blue paw pads or nail beds
- Fast or labored breathing (heart failure often occurs at the same time)
Other causes of paralysis
- Trauma from falls or car accidents
- Spinal cord tumors, often lymphoma
- Infections such as FIP affecting the spine
- Disc disease (less common in cats than dogs)
- Diabetic neuropathy, which causes back-leg weakness and a flat-footed stance rather than true paralysis
What to do
- Keep your cat calm and confined in a carrier
- Handle gently, as cats in pain may bite
- Go to an emergency clinic right away and call ahead
Treatment
- Pain relief, which is urgent
- Oxygen and treatment for heart failure if present
- Clot-prevention medication such as clopidogrel
- Some cats regain function over days to weeks
Saddle thrombus has a guarded outlook and can recur, so your vet will discuss treatment options, prognosis, and quality of life with you. Cats with known heart disease are often given clopidogrel to lower the risk of a clot.
Prevention
- Heart screening for cats with murmurs, gallop rhythms, or at-risk breeds
- Clot-prevention medication for cats with high-risk heart disease
- Secure windows and balconies
Sources
- Luis Fuentes V, et al. ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats. J Vet Intern Med. 2020
- Hogan DF, et al. Secondary prevention of cardiogenic arterial thromboembolism in the cat: the FAT CAT trial. J Vet Cardiol. 2015
- Merck Veterinary Manual: Arterial thromboembolism in cats
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.