One of them is
Jedit Ojanen of Efrava, which creates a 2/2 cat warrior every time it attacks or blacks, and with how often the deck gets stuff out of the library, it isn't too hard to get him. Plus
hungry lynx gives all cats +1/+1 every time a rat dies, which isn't too hard to do with cards like
rabid bite, the other cats, or even just sacrificing the mana dorks. So while it may seem like there are less cats than there should be, I'd say it's still pretty centered around them.