Solid Hardwood, Engineered and Laminate Flooring - stains on wood floors

My husband and i just purchased a new home and upon pulling up the carpet realized the previous owners must have let the dog "go to the bathroom" wherever it wanted to. What should we do to get the stains (and smell) out of the hardwood floors?

Urine stains tend to settle deep into the hardwood. Some floor refinishers refuse to finish urine stained floors because the odor takes the breath away when sanded. Urine stains tend to be permanent. Affected boards usually require replacement, pulling replacement boards from inconspicuous areas like closets. If the staining is extensive, the floor can be recovered with a different floor covering, even wood.

Sealing floors with a couple coats of polyurethane to seal in the odor before installing new floor covering may help. If the urine settled into the subfloor below, sealing the wood floors may not permanently eliminate the urine odor. The odor will be most noticeable on humid days.