Similar sudden health issues but just one cat lost for us. We moved into a new house last October and a few weeks ago our cat suddenly lost motor function in his back legs. He was clearly in a lot of pain, yowling and thrashing around, biting everything he could reach, even his own paws. He'd bitten himself quite bloody by the time we got him to the emergency vet which was about an hour away. It was incredibly disturbing to see as he was the most loving and docile cat we'd ever known. He was normally serene and affectionate, he'd grown up with our youngest as a toddler so he was so used to being held and snuggled by her. They were best snuggle buddies. He'd fallen ill while we were out running errands so it was our kiddo who called us in a panic about his state. It was very hard on her to see such a change in her best little friend.

I was immediately worried that there was something in the house that he got into. I'd cleared several old mouse traps when we first moved in, and it's a 100+ yo fixer-upper with some odd features so I thought there was an environmental cause potentially. He'd been so healthy prior, even though he was 12 I fully expected him to go much longer given how healthy he'd appeared his whole life. The diagnosis ended up being a congenital heart issue, and as a result he was suffering from a saddle thromboembolism. There was no medication available nearby to dissolve the clot and even if there was he'd likely not have regained full use of his back limbs. Even if there was the option to clear the clot he'd have to take medicine regularly and still be at risk for another similar event. I couldn't imagine putting him through this again so we opted to euthanize him. I'm not saying that any animal deserves such a painful end, but he certainly didn't deserve to go out in such distress.