What to do if you find pets in your "no pet" rental

[Jay Mayer]

Hello everyone, 

What do you do when after an inspection or maintenance visit to your property, you find that the tenant got a cat after they moved in? Will it make any difference to you whether there is no visible damage to your property or smells at the moment of inspection in how you react to this event?

Do you terminate the lease or ask a deposit or how do you handle it. 

I appreciate any suggestions. Thank you.