Dreamworks had lots of experience with the characters and environments of the Shrek series that they could reuse in much of the new Puss In Boots film, but the additional new characters required a good bit of new design and development work.  They actually found that their previous fur system used in the Shrek films didn’t scale to having Puss and his companion Kitty as major characters, so they had to find a new system.

On prior films, Dreamworks had relied on a proprietary fur system, but this time around artists used Houdini for much of the fur. “We found that Houdini could handle an order of magnitude number of curves bigger than we’ve been able to in the past,” says Bielenberg. “We had a one to one representation of curves for the fur that were interacting with other objects like the belt. The character FX artists could pull up Houdini and really get a WYSIWYG representation. You could see how the curves were interacting with any forces in Houdini. And four or five simulations could happen in the one package, rather than a serial process.”

via Puss in Boots: head in the clouds | fxguide.