dog in heat or already bred?

Question
Hi
I adopted a female doxie mix from a shelter earlier  this month.  She is about 6 months old at this time. The first appointment I can get for her for spaying is August 1st, unless I want to spend $400.00 for one now at a local private vet.  She was at the shelter for 2 weeks, and they said was not in heat - she has not shown signs of coming into heat yet at my place.  what is the chance that she has not come into heat and been bred already and I dont know yet?  This would have been over a month ago if it happened.  If she comes into heat before August 1st I can keep her away from all dogs easily - but have that slight worry she may already be bred and I dont know... thanks

Answer
Hi Stacey. Because of her age, I seriously doubt that she has even been in heat yet. I know that small dogs tend to go into heat for the first time earlier than the larger dogs, but at 5 months, I doubt that she has. She may end up in heat for too long, so just watch her carefully. One way to tell would be if her vuvla is larger than normal. A puppy's vulva who has never been in heat before will be tiny, especially on her because she's small anyway. Good luck!