Clandestine Rendezvous pet switching.

I picked the Grubby Kitten from the Urchins.

Now i realize i want a different pet, but i already chose Set your kitten to catching rats in the later option:

Can i still Swap Pet somehow? Or get another one?

You can switch your pet anytime that the specific pet related card turns up.

The Grubby Kitten card shows up pretty regularly (I’ve just seen it twice in the last hour). It may take a while if the luck of the draw isn’t on your side, but the chance will come around again