I have an electric underground system that keeps my hounds from following their noses off the farm property. Another system I installed is a regular hot wire system that is about 8 inches off the ground all around my garden. I don't know why the electric doggie sysstem wouldn't work for your cat, since the animals you are describing are all about the same size. With mine, I can regulate it in intensity (because of coat density, size of animal, etc). I don't know about the flea medication for cats....I've used it on my dogs and there's even a brand for horses, believe it or not. Cattle, that's another more complicated process involving deisel fuel and pesticide...long story. Don't suggest it for doggies and kitties!
Cats would have to wear a collar with the sensor in it, which might be a bit of a problem. Also they could jump into trees which the dog can't. But I would assume it would work on a cat in the sense that it would give them a buzz the same way it does a dog (or a human trying it out; I did with a collar I was using with my dog when I couldn't control her on a leash*) and it feels like a defective toaster shocking you.
The stuff from the vet (advantage) is okay right in the back at the nape of the neck, unless another cat licks it - it's toxic to digest but not to assimilate through the blood system. That's why it's important to get it on the right spot, where they can't reach it.
* we had an exuberant golden retriever. 80 lb or so. She was harmless but because of her size, intimidating to anyone worried about their balance, as well as little kids. And she wasn't the brightest bulb on the string. I could not train her to walk quietly with me on a leash, until I got the electronic kind - you carry a wand and they wear a collar with a receiver. If they get out of line you buzz them quickly. It taught her in a couple of weeks to behave herself when walking and we didn't need to use it thereafter. She wore the collar but I didn't take the wand.
Duh...I didn't know how they worked. I just returned from my friend's house. I didn't know the animal had to use a collar, so that's out. I hope my cat & Felix get along (Felix is the dog.) I think he's slightly bigger than she is. Fortunately he stays in the yard during the day, he has a glamorous igloo. His yard area with the electric fence doesn't include the patio, so that could be "her space" outdoors. Starting to house sit tonight.
Kitty, I have heard of a "dumb" dog that just tolerated the "shock" cause she wanted to travel. Cats just aren't that interested in pleasing people the same way a dog is-they make the rules!
I have a buried electric fence wire around our house. My little 15 lb. dog wears a little transmitter on his collar which rings before he gets close enough to be buzzed. What is funny with him is that we've been home from our trip for several weeks, and he hasn't had his buzzer collar on since we returned. He still won't go to the edge of the yard. Another side of the story is that if he reeeeeeely wants to run after something, he'll occasionally endure the buzz and go anyway. The point here is that they are not foolproof.