TL;DR: Feline Aortic Thromboembolism (FATE) is a life-threatening emergency causing sudden hind limb paralysis and cold paws; seek immediate veterinary care at a 24-hour hospital.
What is Feline Aortic Thromboembolism (Saddle Thrombus) in cats?
When a cat suddenly begins limping and has cold back paws, it is frequently a sign of a life-threatening condition known as Feline Aortic Thromboembolism (FATE), or a 'Saddle Thrombus.' This occurs when a blood clot, often originating from the heart, travels down the aorta and lodges where the artery splits to supply the hind legs. This blockage cuts off blood flow, leading to sudden pain, paralysis, or weakness in the rear limbs.
Is my cat having a medical emergency if they can't move their back legs?
- Yes, this is a critical medical emergency. The urgency level is High.
- Cats with a saddle thrombus are in extreme pain and are at high risk for permanent tissue damage, organ failure, or death if not treated immediately.
- Do not wait for an appointment; take your cat to the nearest 24-hour emergency veterinary hospital right away.
How does a photo or video help the vet triage my cat?
- A quick video of your cat's movement allows the medical team to see the severity of the limping.
- A clear photo of the paw pads lets the team check for cyanosis (a blue or pale tint), which confirms a lack of oxygenated blood.
- This visual evidence helps the veterinary hospital prioritize your cat the moment you walk through the door.
Clinical Context (Merck Veterinary Manual)
Arterial thromboembolism, often secondary to conditions causing left atrial enlargement such as cardiomyopathy, hyperthyroidism, or congenital heart disease, can present with pain and paresis or paralysis of the hindlimbs. Clinical signs include reduced or absent arterial pulses (femoral or pedal) in the affected limbs, which are cooler than normal with firm, swollen gastrocnemius muscles. While the tail is commonly unaffected, some cats may only have one hindlimb involved. Diagnosis is based on clinical signs, physical examination, and Doppler blood flow readings of the hindlimbs, with ultrasound potentially identifying the thromboembolus. Mild hypothermia can be a sequela of severe cardiovascular disease and a negative prognostic indicator.
Chapter: Cardiology, Neurology, Emergency
Source: The Merck Veterinary Manual, 11th Edition (Page 143)