Proestrus: The female attracts males, has a bloody vaginal discharge and her vulva is swollen. Proestrus lasts approximately nine days; the female, however, will not allow coitus at this time.

• 发情前期：母犬开始引诱公犬，阴道有血渗出，阴户涨大。发情前期约持续九天，不过，这段时间，母犬并不与公犬交配。