Have you been actively trying to mitigate their loses by getting it ready to re-rent immediately and advertising? You say that their dogs tore up the yard -- but if you allow pets, many judges would tell you that that is normal wear and tear for dogs (depending on the actual damage).
In any case, you said that "it is not able to be rented as of yet." Why not? And, again, have you been actively trying to get it ready?
Also, what was the agreement when they "left in April"? What was discussed? Did they just up and leave or did they inform you that they were leaving early? If it was the latter, you must have discussed the fact that their lease was not up, right? (You should have, at least.)
In my opinion, in cases like this, you are usually better off right from the start to work out some sort of deal to terminate the lease early. You'll have much better luck collecting a month from people that have 2-3 months left right up front -- then going to court to argue that they owe you for the remainder of the lease (and have to prove that you actively tried to immediately get it ready and re-rent it).
So, give us more details and people will give you more advice.
I think a lien is way down the line also. You're going to have to sue them in small claims first, most likely, to first establish that they owe you. If they just bought a house, then they should be collectible, right? Did they have jobs and such?
- John...
--64.25.xxx.xxx