This is also not a Dire Rat in any shape or form.
First, we have to determine what a medium sized quadroped is.
I would go for this.
Then, we need the rat. I would go for this.
Combine.
THATS a Dire Rat. Now tell me such a creature isn't worth the AC 13, 5 HP, attack +2 1d6+2 damage it gets in Next.
If anything, Dire Rats are underpowered in Next.