Yes, they could help a sick/injured STRAY cat. House-pets won't react well to herbs. I suggest if you see a sick/injured cat don't try and use herbs, go get a vet or adult first. However, if there is no one in the area and this is a life-or-death situation with an animal, feel free to collect things that can heal them. If it's not a risky situation where no one is in the area, get help from someone with equipment instead of using herbs/plants.
Ummm i wouldnt try!! im pretty sure they dont i read on a medicine cat herb list not to give those herbs to real cats.... - Hawkbreath