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Most female dogs will go into heat every 6 months or so for about 7-14 days each time. If she is not interesting to the males right now, and she usually is when she is in heat, then I would be concerned about some other issue.
She may have an infection of the vulva or uterus that is causing the discharge. I would be particularly concerned about a condition called pyometra, which is a type of infection of the uterus that can actually be life threatening. The fact that there is a discharge may mean that she has an open variety of pyometra, which would be slower to cause problems.
I would strongly encourage taking her to be seen by a vet, just in case it is pyometra. If that is the problem, then she will need to be spayed as soon as possible.
Good luck and I hope this helps.
Yes, it would be expected that if it were pyometra it would likely have a foul odor to it. However, I have seen some cases of open pyometra that started out as a bloody discharge with a normal acting dog, then progressing to a purulent (pus) discharge. It certainly would be worth getting her checked out or at least trying a course of antibiotics to rule out infection.
The other possibility is that she is still cycling and going into heat, but due to her age, she isn't generating the levels of hormones and odor that is attractive to the males.