I am so relieved to hear it was not a deliberate attack and like Mark wondered whether to mention amputation,
I have a 3 legged cat, Ducha who had some kind of accident before he came to me and they tried to save the leg but it did not work.
he is a lovely happy little monster and rushes around like a lunatic and once they have recovered from the amputation they do not need special care, except to be aware that some things they cant do as well as they used to.
Its Duchas right back leg that is missing and he has his own special way of using a litter tray and its important they do not get overweight cos that puts a lot of strain on the remaining legs. He also needs the side of his head and ear rubbing and grooming cos he cant scratch there so loves it being stroked and played with and chin strokes.
he finds it too hard to be on a lap cos he must not feel comfortable I think but dont know if that is just Ducha and dont think he had much , or any lap time before he came to me after he lost the leg.
I am sure this will be the best option for Casper and apart from the recovery time I dont think your mum needs to be worried. although he should not be allowed out on the road. Ducha cant jump as high so when he goues out he is garden bound although when he first came here he used to go out a lot more and did see him in neighbours garden and coming back across the fence, ,,,,,,,,,,,he scared me terribly cos he sorta jumped at the fence and clung on with front paws and heaved himself over and then plonk back to the ground........so pleased he doesnt do that anymore! Didnt know he could until I saw him.........sigh
Best wishes for Casper