older house cat attacked by feral ...help..no vet

Our older 17yr calico female got out tonight and got attacked by another
cat.
We interrupted before the feral cat could kill her.
She is small, deaf and bit senile I think. It 2am and there is not a vet
with emergency in our area.

I grabbed her and brought her in the house and inspected. There were clumps
of her fir on the ground at the fight seen. Look like she had a puncture
wound in her neck but it had stopped bleeding. She would hiss and growl if
we came near her. When she tries to walk, she has much trouble on her back
legs although there is no outwardly sign of injury there. Immediately after
the fight. After 45 minutes she was not frightened of us any more and we
could touch her. She wobbled over to a favorite spot she feels safe
in...its dark and confined. We are just letting her rest now and checking
every 1/2 hour. She seems to be alert, but just laying with her eyes open.
Everyonce in a while will do a pitiful meow and when I appear she stops and
settle back down. I'm not sure if she is waiting to die or in some sort of
cat shock. She wont eat when offered cat snacks.

Any experience with this sort of cat shock?

PS. how does one trap a feral cat?