Tenants have a pet, violated lease, leaving in 6 weeks

[Cali Skier]

So we have received word from our tenants that they wish to vacate in 6 weeks, at the end of their lease.  We notified them that we would like to come review the property in the next week so that we can assess when it will be available for the posting.  

We just happened to be in the neighborhood and drove by the property and saw a pet cage in the window, dog likely.  They did not have a pet when they took possession and never told us it was there.  So they have violated the lease terms and I have the right to keep the deposit.

I assume when we see the house the animal evidence will either be hidden or apparent.  Either way, my approach is to be very cool.  My attitude right now is as long as the property is left as it was when we turned it over the them originally and its ready to go for the next tenants, everything cleaned up, no animal scratches, holes in the carpet, bad smells, picture holes painted, carpet cleaned, oven, refrigerator, etc., then I don't really care.  Leave it nice and we can part ways and I will very likely give the deposit back if there is minimal effort from me and the house does not stink.

What say you guys?