Wet dog Smell (NOT URINE OR MOLD)

[Cal C.]

This is a new one on me.   I have a vacant house which has a serious wet dog smell, it is definitely not a urine smell.  I have had several people including the carpet cleaner, my handyman, my realtor, and potential tenants tell me it smells like wet dogs.  Much of the house has been repainted and the carpet has been cleaned twice with a deodorizer put down each time.  However, the smell still remains.  Normally, wet dog smells don't linger and when they do cleaning the carpet and/or painting the walls takes care of it.  

Obviously, I could spend a couple of grand and replace the carpet and pad which would get rid of the problem unless it is in the sub flooring, but I don't want to spend the money unnecessarily.  Also, I have some great applicants who want to move in right away and no they are not being evicted from their current place.  Since it will probably take me several days to line up new carpet or pad only replacement I may lose these applicants.  

Options as I see them.

1) do nothing and hope the smell goes away on its own or I find a tenant without an olfactory sense.

2)  Replace the carpet and pad (hopefully I won't have to put Kilz on the subflooring also). 

3) possibly replace the pad only.

4) Get the carpet cleaned for the third time (for free).

Any other suggestions? 

Thanks!