I describe some about pet cage expansion...
First every races have 1 box for pets.
Werefox get another box at level 7 quest.
You all have chances to add 3 more boxes by accepting the quests from NPC pet trainer.
If you are not a werefox, you need not add any.
1st step
Pet trainer ask to bring 30 green grasses.
Some low level turtles or grass eating creatures may drop it, but it's quite rare drop.
lvl 30 fawn also drop it. tho it still belongs to rare,
* I recommend leveling till you gotta be able to slay this fawn, if you want to figure it out by yourself.
When you could find some grasses for good price at auction, of course it is better you get em.
2nd step (it will be unlocked, when you complete 1st step)
Pet trainer ask to bring 50 wild fruits.(don't know what it will be called in english)
Some creatures around lvl 38-54 may drop it. It's rare.
3rd step (it will be unlocked, when you complete 2nd step)
Pet trainer ask to bring 100 spiritual turves.(don't know what it will be called)
Some high level creatures (at least lvl 58, mostly around lvl 70) may drop it. of course it's rare drop.
You need pet cage immediatly? or you need more? Then you open the mall's gate.
You can have pet cages up to 10.