Poor kitty cat I am so sorry that happened. I must say that it happened to me before, with my old RB Kilo. My 2 dogs, lived with Kilo for a year, and loved him. He was not ill or anything, just one night they attacked him, and I didnt get to him fast enough. He died about 10 minutes later. That is why I will NEVER EVER AGAIN have a dog and cat in the same house. I dont trust dogs at all with cats. They were so loving one minute, and just turned the next. We still have the 2 dogs, but they are OUTSIDE only now, because of the incident.
I hope your friend finds a way to comfort herself. I am so sorry again