Pet odour is the most over-promised service in the cleaning trade, and the reason is simple: masking a smell is easy and cheap, removing it is neither. A fragrance treatment smells wonderful for about two weeks and then the problem returns, usually on the first warm day.
Understanding why it returns is most of the battle, because it explains what a genuine treatment has to do.
Why the smell comes back
Urine dries into crystalline salts that sit in the fibre, the backing, the underlay and often the floorboards. Dry, those salts are more or less odourless. When humidity rises — a warm day, a damp day, or immediately after someone adds moisture by cleaning — they reactivate and release ammonia and other compounds.
That is the cruel twist: a surface clean that adds water without removing the salts makes the smell worse for several days. Plenty of people conclude that odour treatment does not work, when what actually happened is that half a treatment was performed.
It also explains the seasonality. Households often tell us the smell appears in spring. It was there all winter; the humidity simply was not.
The mark is smaller than the problem
Liquid spreads as it soaks. What lands on carpet as a small patch typically reaches two or three times that area in the underlay, and a good proportion reaches the subfloor. Cleaning the visible patch removes the stain and leaves the source.
A UV lamp shows the true extent, because urine fluoresces. Turning the lights off and scanning a room is routinely a shock — marks nobody knew about, and known marks that turn out to be three times the size.
On upholstery the same applies through the fabric into the foam. A cushion can look fine and be saturated underneath, which is why a cushion sometimes has to be treated from both faces.
What a real treatment involves
First, find the full extent with UV. Then apply an enzyme treatment deliberately and generously, so it reaches everywhere the urine reached — which means applying more liquid than feels comfortable, not less. Enzymes digest the organic compounds that produce the odour, and they need dwell time, typically twenty to thirty minutes, sometimes longer.
Then extract thoroughly, and re-treat where the contamination is heavy. In severe cases the carpet has to be lifted so the underlay can be treated or replaced and the subfloor sealed, because no amount of surface work reaches a floorboard.
That last step is the honest dividing line. If a dog has used the same corner for two years, the underlay is the problem and we will tell you so and quote for it, rather than charging you for a treatment that cannot reach the source.
Cat urine is the hard case
Cat urine is more concentrated than dog urine and contains compounds that break down into particularly persistent odour. It also tends to be deposited repeatedly in the same place, so contamination is deep rather than spread out.
It responds to the same approach — UV mapping, enzyme, dwell, extract — but more often needs repeat treatment and more often reaches the subfloor. We will give you a realistic assessment after inspecting rather than a confident promise over the phone.
One practical note: if a cat has started using a particular spot, removing the odour properly matters for behaviour as well as comfort. Cats return to places that still smell like a toilet, even faintly, and a masked smell is still a signal to them.