Dog urine

Urine stain removal is seldom an easy task. Urine contains many elements, including at least one dye. Bacterial work upon it and during the decomposition there is a transition from mild acid to strong alkali wich results in a 'scorching' effect that can lead to a permanent colour change. A felt backing can complicate things by providing a reservoir for the original deposit which can extend well beyond the area of visible staining.
 
The dual problems of odour and dis-colourisation cannot always be resolved in a single visit and the several different approaches need to be tailored to the problem and the customers requirements. remember also that a minor odour problem can be exacerbated by any attempts at cleaning.
 
In this particular instance I would suggest that you start with a heavy treatment with a product such as Prochem B153 Urine neutraliser. Do not simply dampen the pile - the product need to penetrate as deeply as the urine. Get your wellies on and use a 'grape pressing' action to work in the product - if it does not squelch, you have not applied enough.
 
After a dwell period, if you do not have a water claw, use a hand tool to draw as much liquid from the backing as possible. Only when you have extracted all you can, start rinsing.
 
At this stage you need to decide on alternate next stages.
 
To tackle an odour problem a bio-enzymic approach makes sense - a live bacterial *ocktail such as Micro-Clean. But having used B153, which contains sterilisers, this cannot be applied until the carpet is completely dry at all levels - which could take a week.
 
If odour is not a concern and you want to move strait to cosmetic improvement you could use citric acid. This really needs to be left on the carpet to dry in for best effect. Since citric acid will leave a sticky residue, a second visit will be required to rinse out.
 
Another approach would be to use a reducing agent. The most popular of these is sodium metabisulphite. Before using this product ensure that any acid residue from the Urine neutraliser has been thoroughly rinsed off, otherwise the production of sulphur dioxide and sulphur trioxide gasses can reach a level where the room has to be abandoned. This product is rinsed out after an extended dwell.
 
An alternate approach would be to uplift the carpet to enable treatment from the back and renewal of underlay if required but it sounds that you customer would not wish you to go to this extent.

Buy a gallon jug of 20% Hydrogen Peroxcide