Installing your artificial grass correctly will go a long way in helping to deal with pet urine odours. Make sure your sub-base is permeable – liquid needs to be able to pass through the sub-base and drain away quickly, consider laying a sub-base of MOT type-1 roadstone to a depth of 80mm to 100mm. It’s also important to make sure your weed membrane is laid UNDER the sharp sand or granite-dust laying course, and not directly under the grass, this enables faster draining and avoids any urine getting trapped between the weed membrane and the grass backing.