Unapproved pet number 2 for tenant...

[Joseph Torres]

OK, so I already know my rights and what I'm allowed to do I'm just curious on what steps I should take.

Scenario: 

Tenant has one approved pet (small dog) which is called out on the lease (even by name). There is a pet deposit that has been paid and a monthly pet fee which they pay. That is all fine but recently I went to pick up rent money they left it inside when they weren't home. I have a key and approval to enter the apt. This was the agreement for that day.

Issue: 

When entering apt. I had to use the bathroom quickly. I had to go through another room to get to the bathroom and noticed a litter box that was full in the bathroom. Upon leaving towards the front door I noticed there was a cat clear as day just lounging on the bed. This tells me this cat has been living there for some time. I did not take any pictures as it didn't occur to me until just now. 

Question:

What is the best way to handle this situation? I entered with them knowing but had to use their bathroom. I don't want it to be assumed I was snooping. Do I just bring up that I saw the cat and litter box (they will know I had to go through a closed door) and pull rank or is there a better way to handle this? At this point they are in clear violation and I can either have them pay more for the second pet or ask them to leave which I prefer not to do. I can tell you right now their security deposit is mine since the carpet in one room is ruined which is why I never allow pets.

FYI. I inherited these tenants.