
There is a bitch pheromone that vets use when getting semen for AI when there is no teaser bitch available. I still think it inadvisable, if the bitch isn't giving off the right scents then something isn't right with the ovulation cycle and it would be a pointless exercise in getting a mating under such circumstances.
Interestingly enough I know of a bitch who was presented to the dog on two seasons but the very eager stud only showed minimal interest. They did get a mating on both occasions but no puppies. third time the dog was really eager for her (I'd have been trying another dog by now, but he had sired big litters before and after mating her). She went on to have a litter of 10. It subsequently turned out that the bitch had a slightly underactive thyroid, which explained why she gained weight so easily despite loads of exercise and minimal food even for our reed. It does appear to e the case that an under active thyroid will interfere with ovulation/fertility so this might be worth looking at in the bitches case. If it is a northern breed it needs to be remembered that low normal is actually under active for a Spitz breed. It might be worth finding out what are the normal levels in your breed.
Another thought is that the bitch may be erratic. I have known a bitch that for her first litter (after missing a previous season) was mated and whelped to a day 7 mating, but wasn't ready until day 15 the next time she had a litter. so it might be as well for this bitch to stay with the stud from the start of her season, cheaper than doing lots of investigations, which can be left until later if still no mating.