Pound for pound cats are pretty fierce. My cat (12-13 pounds) got into it with a good sized labrador retriever once.

By the time we got them apart: the dog was bleeding, the dog's owner was bleeding, I was bleeding. Everyone was bleeding except the cat.

http://wh40k.lexicanum.com/wiki/Jokaero

Too far? Heretic!

A cat companion would need better independent AI. See, you don't command cats. You request. Very politely. And very carefully. Technically, you would be the cat's companion, in fact.

What about... Raccoons?

Better Thieves, cooler companions and they probably all have firearms training.

Some cat species are social and some are not so it's not clear that cats would die because they always hunted alone (after all Deathclaws do that right?). In fact, much as I love housecats, what you really want as a companion is a Bengal Tiger. Maybe a talking one since this is Fallout. An FEV/radiation enhanced Tiger mutation would probably hunt deathclaws for sport. The only thing a pack of dogs would be wondering is how fast they could run in the other direction.

There are so many other animals that have mutated and grown much bigger than their pre war ancestors so why not a cat. Heck it doesn't even need to be a lap cat why not a lion, cheetah, or leopard. I could just see it looking like Battle Cat from the He-Man cartoons for those of you that are old enough to have seen that one.

I told you to stop making up animals!

A cat won't be into traipsing around the countryside with you though, it'd prefer to hang around a home base.

For its size a cat is stronger than a dog, cats have a little over 4 times the bone & muscle density of an average humam, dogs only have around 3 times the muscle density & about 2.5 times the bone density.

I killed the Covenant cat after I killed everyone in Covenant and Deezer.

The cat was the only survivor of the Covenant Massacre in my game. Now he rules that town!

yep id love a cat companion

personally id be happy if it did nothing but just follow you around, but also why not kinda like cat familiars like in the dnd games (like nwn/nwn2) could grant you extra stealth or pickpocket or lock pick ability or something? doesnt have to be combat

or could even have a cougar/mountain lion companion similar to dogmeat? or even more exotic from zoos tiger/leopard/puma/lion etc

Cats are intelligent enough to recognize the threat of the Institute and would conceivably lead a mission as needed.

Or, you know, synth cat. Also possible.