TL;DR: Sudden hind limb paralysis in cats is a life-threatening emergency usually caused by a blood clot (saddle thrombus) and requires immediate veterinary intervention to manage extreme pain and prevent permanent tissue damage.
What causes sudden hind limb paralysis in my cat?
Sudden paralysis in a cat's back legs, often characterized by the cat dragging their hind limbs, is frequently caused by a condition known as Feline Aortic Thromboembolism (FATE), or a saddle thrombus. This occurs when a blood clot, usually originating from the heart, travels through the aorta and becomes lodged at the junction where the blood supply splits to the two back legs. This blocks blood flow, leading to sudden loss of function, cold paws, and significant distress.
Is sudden back leg paralysis in my cat a medical emergency?
- This is a high-level, life-threatening, and extremely painful medical emergency.
- Transport your cat to the nearest emergency veterinary hospital immediately.
- Do not wait for a regular appointment or monitor the condition overnight.
- Immediate care is vital as the lack of blood flow can cause rapid tissue damage and heart failure complications.
How can a photo or video help the vet triage my cat's condition?
- Capture a brief 5-10 second video of your cat attempting to move so the triage staff can witness the exact onset of symptoms.
- Take a clear photo of the paw pads on the affected legs to help the vet identify signs of cyanosis (blue or pale pads).
- Provide these visuals to the emergency team, as symptoms may change or progress by the time you arrive at the clinic.
Clinical Context (Merck Veterinary Manual)
Sudden hindlimb paralysis in cats can manifest as posterior paresis or paralysis, potentially accompanied by urinary and fecal incontinence due to sphincter control loss. Diagnosis relies on clinical signs, physical examination, and Doppler blood flow readings of the hindlimbs. Ultrasound can also identify thromboemboli; misdiagnosis of neurologic abnormalities as arterial thromboembolism is common. Pathologic changes distal to the mid-to-lower thigh are characterized by focal muscle necrosis and sciatic nerve degeneration. Management includes analgesics, nursing care, and treatment of underlying diseases such as cardiomyopathy. Anticoagulants like heparin are used to reduce further thrombus formation. Neurologic deficits may improve within weeks, but complete recovery can take months, and permanent deficits are possible. The prognosis is guarded, with a high mortality or euthanasia rate during the initial episode.
Chapter: Cardiology
Source: The Merck Veterinary Manual, 11th Edition (Page 1245)