Breeding my Ger. Shep

Question
My  2 1/2 yr. old Ger. Shep. bitch is in heat and we are  trying to get her bred here on our premises.   This is day 13 we believe after she started bleeding and she is doing the same thing as last Fall when we tried to breed her with the same stud dog. She stands, flags, etc. but will not stand and let him enter her.  I tried holding her by her collar and last year I tried using a hay bale to assist.  He is a little taller than she is.  She always comes in heat every 4 months. Would that have something to do with the situation?  I realize tomorrow she might breed but I am afraid I am going to miss her again and I prefer for a natural breeding. I decided to leave them together tonight to see what happens.  I have never had this happen with my other dog and she had 4 or 5 litters for me.  Thanks.

Answer
Every four months is not normal but it does happen. My best advice is to take her to the vet for a progesterone screening and cycstology. By doing this every other day you will get an accurate timing for hormonal rises and when she will be ready to breed/ Don't leave them together. You're going to frustrate your male and possibly cause injury to one or both of them. Putting them together an hour or so in the morning and evening supervised is the best way to achieve a safe tie. Especially with an uncooperative bitch. Since she has a history of odd cycles and not standing I would take her in for the hormonal screening asap
Good luck
Cindi