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Since there is only 3 "buy a pet" action spaces, It is possible for a player to not buy a pet in the first round, putting him at quite a disadvantage. And If he can't buy a pet in round 2 either, he is left saleless for round 3.
This was actually brought up in playtesting. However.....
The player who doesn't get a pet can clean the cage.
That player normally purchases a 2nd cage.
A second cage is actually more important than a pet early on.
We had 3 games in a row during playtesting where the player who didnt get a pet won the game.
So, it isnt an issue.