It's called jealousy the menstrual cycle of female dogs, which is associated with bleeding from the vulva. This cycle is 21 days and occurs every six months . During bleeding, should maintain hygiene convenient, washing the vulva twice daily with mild soap. The first cycle will be presented to the eight or ten months old and should know that it is recommended that the dog get pregnant in the first period, is too young. The optimum is to wait at least until the third heat.
If it is intended to cross into the female should be borne in mind that the first eight or ten days in the period corresponding to the preparation for the pro-estrus or ovulation. The subsequent eight or ten days are called estrus and is the phase in which the bitch ovulates and accepts the male, so the ideal time for reproduction . Typically at this stage bleeding and gone, but not always.
Not easy for the dog to get pregnant, since many of them are dominant and aggressive, so they will not accept a male in his territory. So it is more convenient than the female is transferred and that the male is in its territory who do not feel intimidated. Also, when the dog is gilt, the male should have experience with.