TL;DR: Sudden paralysis of a cat's hind legs combined with cold paws is a life-threatening emergency known as a Saddle Thrombus that requires immediate veterinary care. This condition is extremely painful and signifies a major circulatory blockage.
Why has my cat suddenly lost the use of its back legs and developed cold paws?
When a cat suddenly loses the ability to use their back legs and has cold paws, it is most often caused by a Feline Aortic Thromboembolism (FATE), commonly referred to as a Saddle Thrombus. This occurs when a blood clot, usually originating from the heart, travels down the aorta and becomes lodged where the artery splits to supply the hind limbs, effectively cutting off circulation.
How urgent is it if my cat cannot move its back legs?
- This is a critical, life-threatening emergency that is extremely painful for your cat.
- Do not wait for an appointment or try to treat it at home.
- Transport your cat to the nearest emergency veterinary hospital immediately to address the pain and attempt to restore blood flow.
How can taking a photo of my cat’s paws help the emergency vet?
- Take a clear photo of your cat's paw pads while you are preparing for transport.
- Note if the pads appear pale, blue, or purple, as this provides immediate visual evidence of the severity of the circulatory blockage.
- Providing this photo allows hospital staff to prepare necessary stabilization equipment before you arrive.
Clinical Context (Merck Veterinary Manual)
During triage, if a cat presents with cold paws and inability to stand, evaluation should include assessing the level of consciousness (stupor, coma, seizures) and pain (vocalization, changes in behavior, tachycardia, dilated pupils). Airway, breathing, and circulation must be evaluated sequentially, followed by examination for hemorrhage. Doppler ultrasonography can help evaluate blood flow in the distal aorta and femoral arteries, and may indicate pathologic changes distal to the level of the middle to lower thigh, characterized by focal muscle necrosis and degeneration of the sciatic nerve. Treatment may include analgesics, nursing care, treatment of underlying disease, and anticoagulants.
Chapter: Emergency, General Principles, Cardiopulmonary
Source: The Merck Veterinary Manual, 11th Edition (Page 1659)