Urine and dog poop on a wood deck
 

My client have two dogs who are accustomed to doing their business on their deck, we built this deck for them 4 month ago and we just applied this week 2 coats of stain (Behr) ligth color.
I scrubbed it today with soap and water and I could not get it clean. Is there something can put over the stain (paint) to help clean it better?. I don’t understand why it is impossible to get the dirt off.

Urine contains amonia, which stains the timber, sometimes a strong alkaline can remove it (white vinegar), it's a bit hit and miss though and can make the stain darker.

There is a product called netrol that will probably shift anything http://www.decorireland.com/Owatrol-Netrol

I don't know if it's available over where you are.