An animation file is available at Jackie Lewin's site, Stuff for Poser. Look in the Poses section.

Unfortunately, the site's link to the animation file doesn't work due to a typo (the .zip extension should be lowercase, rather than all-caps. Check here for the corrected link.

Credo Interactive (the maker of Life Forms Studio) sells a CD collection of 14 cat animations made specifically for Poser.