My female border collie

Question
QUESTION: My female Border Collie will not breed. She will come in
but everytime my male  Collie gets close to her she will fight him off. She is 5 yrs and he is 3yrs. old .  She has never let a male near her when she is in heat. I don't understand this. He will not leave her alone but when she start getting mad he will back off but for only a min.
She is in heat right now but will not take him. What do I do?

ANSWER: I also had a bitch here I could never breed for the same reason. She would attack the males through the babygate and bite any body part she could reach. Heaven forbid if there wasn't something between them. I thought about AI-ing her, and you could try that also, but then, do you really want to possibly reproduce that attitude?

If you decide it is worth the effort, your vet or a reproduction specialist should be able to help you. Progesterone testing is the best way to determine ovulation time.

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QUESTION: Well thats not her case. She is a very loving dog.  Great with everybody and everything. Extemely smart and great with the live stock she is a working dog alond with the male. My female get along great with my male.  the are like best friends. They play and work together all the time. It's only when she goes into heat that she will attack him.

Answer
Of course it is. She is doing the exact same thing my bitch did.... attack any male that even *thought* about coming near her when she was at any point in her heat cycle, prime or not. That was the second bitch I've had like that over the years (different breeds). Those bitches of mine were perfectly fine, too, when they were not in season. As I said, either AI her or have her spayed, but do consider that you could well reproduce that attitude.