Hi, I'm sorry to hear about your cat.
Can you answer a couple questions:
1. How old is this cat?
2. How is he/ she breathing?
3. Any history of heart disease?
4. Is he/ she moving the legs or just dragging them?
Hi, thanks for the info.
It sounds like your cat suffered from FATE (feline aortic thromboembolism) or a "saddle thrombus." This is where they have blood clots that form in the heart and eventually break free and get stuck where the blood vessel (aorta) branches to go to each back leg. This results in sudden loss of blood flow to the legs and instant paralysis. The condition is extremely painful for 2-3 days, then the nerves die and they are no longer painful. Many treatment options have been attempted, but there is no known cure. Euthanasia is often indicated to alleviate pain/ suffering.
With that said, since it has been 3 days, we are likely getting over the painful part of this. There is a chance that she will regain function to the back legs, but it often takes 1-2 weeks or longer. There is a nearly 100% chance that she will have a recurrence within the next 6-12 months, however.
What I would do for her at home is good nursing care- bringing the food/ water to her. Helping her in and out of the litter box. Physical therapy by flexing/ extending and massaging the rear limbs.
If she starts having trouble breathing, then she likely threw a clot to the lung. If she has a seizure, then she likely threw a clot to the brain. These are very likely as some cats will begin throwing many clots.
Hope this helps clear things up, I'm sorry again as this is a terrible disease in cats and one we see way too often. Let me know if you have any other questions.
You're welcome.
I'm sorry again.
Cat Veterinarian
DVM, Emergency Veterinarian; BS (Physiology) Michigan State Univ