A 5 month old kitten's breath really shouldn't be stinky. Sometimes that is a sign of a medical problem and I suggest you ask your vet about it the next time you go in. At 5 months, she should be just about ready to be spayed (unless you got her at a shelter where they spay early)so that would be a good time to ask. My youngest had a breath problem and it turned out to be a sinus infection. Once she had antibiotics for that, it cleared right up. But it is still a good idea to get her used to having her teeth brushed and to continue good oral care so she won't need dental cleanings at the vet as often when she gets older. I think the only difference in the cat and dog stuff is that the flavors are made to appeal more to cats in the cat products.
"A kitten is infinitely more amusing than half the people one is obliged to live with in the world"- Lady Morgan