I am currently experiencing this problem, very confused! I'm waiting to hear back from the vet for advice, but in the meantime would appreciate any experiences or ideas.
My great dane female is 20 months old. Her vulva has been somewhat swollen the last 3 days but no blood.
Her heat history: The peak of her previous (second) heat was Jan 21st, and she began bleeding within a day of the first signs of swelling and she swelled very large. Her second heat came 8 months after her small half-heat which occurred at 6 months of age (light discharge with unnoticeable blood flow and light swelling). Since her last heats were 8 months apart I did not feel the need to be concerned when July 21st passed by with no signs of a heat. Also, I have had smaller female dogs with heats 8 months apart and the vet said that was common.
However, I cannot figure out if she is actually in heat right now. My male great dane usually becomes obsessed with a female from the moment they start swelling and bleeding, at this point he just sniffs her and walks away, it could be he knows it will be awhile before the peak, or could she be lightly swollen for another reason? She has one or two 'acne' bumps on her lips and anus right now but that is supposed to be normal and usually comes within a few weeks to within a few months prior to a heat.
So, I need to determine if I should be counting to peak from first day of swelling or first day I see discharge; the date I take her to the stud is dependent upon this, hopefully my vet will have a magical wand to let me know if she will be peaking sooner than later.
Other questions: Are breedings just as successful and healthy when conceived on a light heat as opposed to a full-blown heat? I've been looking for answers on this and haven't had much luck; if anyone has a link to some helpful info I would appreciate it!
ALSO, I heard something about how it is possible for a female to show a false heat about 3 weeks prior to a full heat; is that true?
P.S. There was a very small amount of clear discharge when I dabbed her vulva with a Kleenex.
Since your bitch is only 20 months old, she is not old enough to breed. She must have her OFA, CERF, BAER and full vet test for her heart and a complete blood panel done. Yes, she is very likely in heat, and in such a case you would count from the first day you noticed the swelling. I would not advise you to breed her though.