Rat

Rats are small animals which can be found almost anywhere. They are best found inside the Lumbridge Castle (Floor one). You must also kill one to get the tail in Witch's Potion.

Cats
Players who have a cat or a kitten can tell it to chase vermin, in which case it will try to attack any rat in range. Also, if you have a Rat pole, a rat will be added to it each time a rat is caught by your cat.

100% Drops

 * Bones (only the Stronghold of Security)

Other drops
A player has to be doing the quest to even get these drops and a player can only have one of each at a time.
 * Rat's tail (used in the Witch's Potion quest)
 * Rat bone (m) (used in the Rag and Bone Man quest)

Trivia

 * The examine text is based on the Discworld books by Terry Pratchett, who goes into detail describing the ways dwarves eat rats.
 * A Rat bone, which differs from the usual bones dropped by rats, are rare drops used in the Rag and Bone Man quest. This bone cannot be buried. Surprisingly, rats in the Stronghold of Security drop bones, while rats everywhere else in RuneScape do not. It is unknown if Jagex meant for this to happen or if this is a glitch.
 * There is a rat in Surprise Exam!, however it is the "class pet" and you cannot attack it.
 * Rats do not appear on the minimap.
 * Rats are, perhaps, one of the weakest monsters in RuneScape, along with the level 1 Spider.