Bamboo is technical a grass not a wood species. As such, much of the bulk of the flooring is comprised of glue or other binding agents. These binding agents do not take stains well. Therefore, trying to stain the floor will likely be futile. Additionally, pet urine tends to leave dark rings which are very hard to both sand out or stain over unless you use a very dark stain. Unfortunately your best best is to cover the floor with carpet, a rug and replace it. Are you familiar with Flor by Interface. These are carpet tiles that you can make customizable rungs from, consider this affordable option for concealing the stains.

I'm afraid to say, you have found one of the weaknesses of bamboo flooring. You are better off concealing the floor until you are ready to have the the whole thing re-done. The urine stain is permanent and will always retain some smell of urine.

Becareful when having bamboo taken up. The adhesives can be made from Urea Formaldehyde and the finish is quite often aluminum oxide. Both of these chemicals can cause health problems if they are thrown into the air as in construction dust!

I have a similar dilemma. I came across a process that is used to darken a bamboo floor. They don't strip or stain the bamboo. The floor is etched, and then a dark color sealer of sorts is applied as a hard finish. I am guessing it is like a polypropylene. I've spoken to the company who does this refinish. They sent me a photo of a floor that they had redone. I'm probably going to have it done to darken my yucky old, caramel colored bamboo floor. Check out: Mr. Sandless Company to see if it is in your area. mrsandless.com

Mrsandless is an option so long as the finish underneath can handle the mrsandles finish. I would guess that most can...I know my German factory finish would bubble and peel with something as aggressive as MrSandless.

Mr Sandless is a glorified screen and recoat. Save your cash!!! You won't get the results your looking for from mr Sandless. I keep refinishing his messes and the customer in trying to save money ALWAYS spends more going that route but if you don't care to heed what I say then go ahead and try me Sandless out......