my male daschund is acting completely different from the first time my bitch was on heat. He is barking constantly and always trying to hump her, more so than the first heat. Why is this so? They are both 2 years old approx and she has had one litter already by him. Not sure what to do. Do I leave them together for her to get fed up and fight with him, or do I separate them? Have only been breeding for one litter so would appreciate some advice.