A little known hexing fact is that you can change a pet's profile pic.
The Pet Editing Manual (included with LNZ Pro) has information about this.
This is changed in the pet file. (I believe that changing the breed's adoption center pic requires you to export a pet's pic via PetzPicFactory and pack it into the breedfile. It doesn't seem to change automatically and many people still leave the original picture in their hexed breeds.)
This page on Waverly Academy Petz has pictures of some of the frame numbers.
There are 493 Catz animations (numbered 0 to 493, inclusive.) The final frame number is 16039. (A higher number will crash the game when you put your pet away to refresh the image.)
The last dog animation is DOG444.
I love the unused/unusual animations, and the idea of changing pet profile pics. So I made more pictures to use as a reference. The more unsual animations would be perfect for OddPetz.
Instead of learning how to parse the animation files, I made an estimate of which frame numbers go to which animations. I used it to find the oddballz exploding animations. [Insert pic of adorble exploding calicos here]
You can view the animations in the Petz Workshop.
LnzLive run/download this code to get a viewer for the animations.
The files are in the the Resource folder, in the Catz/Dogz Rez.dll files, in .rsrc\BDT. Extract with a program like 7zip.
The github page has link to the viewer online; it has all the animations. It looks much better than the Petz Workshop.