Dire wolves may be the paradigmatic dire animals, but dire rats are probably the ones you first saw in the dungeon. (I seem to recall a nice illustration of one in the D&D Basic Set red box.) And now that swarms are all the rage, regular rats are a bother, too.
A hero’s career does not have to get off to a glamorous start. When a rampaging red dragon firebombs their town, a group of ne’er-do-wells are too young to take up arms against the monster. But when the dragon smashes the abandoned basilica and sets it ablaze, there is much the young heroes can do, including rescuing townsfolk trapped in the rubble and exterminating the rat swarms that come pouring out of the walls.
“The Stunning Rodentia of Seamus, Adventurer” read the signboards posted all over town. Seamus’s trained piebald dire rats are a hit until one of the stars contracts filth fever. Soon all the rats are half-mad and sickly, and the improvident Seamus releases them rather than put himself at risk nursing them back to health.
A wererat street urchin finds he can no longer empathize with dire rats. Perplexed, he follows his former friends deep into the sewers in rat form, where he finds them chewing on strange fungi and weeping stones. He also finds morlocks, and both discoveries terrify him so much he is willing to risk asking for help.
—Pathfinder Bestiary 232