As with the Petz 3 and Petz 4 games, you can "easy-edit" the mice in your game as well as the stick, milk etc. But the easy-edit method needs a small change to be made inside your game's Petz 5 Rez.dll file.
I'm not going to give you an "exploded" download of the full .dll file for this, because it's way too big. But I can provide you with this cut-down easy-edit version which I use myself; be careful to read the instructions on installing it, and make absolutely sure that you put your original Petz 5 Rez.dll somewhere safe first.
NOTE: This downloaded version of the file will overwrite the one that's in your game if you've not moved that one, and it will crash your game if you have not made sure to install it as per the included instructions. If you got it wrong and did not put your original somewhere safe I will not send you a copy; 30 megbytes is more than I'm willing to send! If you mess it up, you'll just have to re-install the game.
Now, once you've downloaded the file you have two options... you can either throw away my small .dll from the zip, install the included zip of extracted files, and follow the instructions that I produce on this page for editing a couple of bytes in your Petz 5 Rez.dll, or you can put your Petz 5 Rez.dll somewhere safe and run the game with my cut-down .dll. The problem for some people with this second option is that you cannot play most of the mini-games with it, and pets come out of the wall at the Adoption Centre. Everything else works normally, and it's what I use in the game anyway. The problem for some people with the first option is that they are terrified of the words "hex editor" ;-)
Okay, if you've decided to throw away my dll file and just install the "art" and "ptzfiles" files, that's cool. Here's what you want to alter in your Petz 5 Rez.dll in the hex editor; one letter in each of L.N.Z and S.C.P in this area of the file:
or it might look like this in your particular .dll file:
Just alter those two highlighted letters to any other letter. Now, install the zipfile that's inside the Petz5Easy-editMiceEtc.zip which you just downloaded. Follow the instructions carefully, and then start the game. There ya go -- enjoy editing what is editable and swapping whatever is swappable... You may want to take a look at my Mad Scientist's Petz 5 Sprite-swapping insanity page for info on how to swap SPR files.