RAT

Rats of all sizes and colors are found everywhere from forest wilderness to city sewers. Although cowardly, a trapped or cornered rat will fight ferociously. When starved, rat packs will attack anything alive in order to feed. 

As is true of giant rats, typical rodents of this sort have a filthy bite with a 5% chance of causing a serious disease unless a save vs. Poison indicates otherwise. Normal rats fear fire, but, when driven by hunger, they will sometimes brave it.

Rats of all sorts are common, and the giant Sumatran sort are a plague in many places such as crypts and dungeons. Their burrows honeycomb many graveyards, where they seek to cheat ghouls of their prizes by tunneling to newly interred corpses.

Any creature bitten by a giant rat has a 5% chance per wound inflicted of contacting a serious disease. If such infection is indicated the victim is diseased unless a saving throw versus Poison is successful.

Giant rats will avoid attacking strong parties unless commanded to fight by such creatures as wererats or vampires. 

They are fearful of fire and flee from it. 

Giant rats swim quite well, and they can attack in water as well.