At this time, the bitch's vulva will swell like a peach, which is caused by hormonal changes in the dog. The vulva will swell. Bleeding usually occurs in 1 to 7 days, and 7 to 15 days is the best time for breeding. Generally, the duration of vulvar swelling is 15 to 25 days. This is a normal physiological phenomenon, so don't worry too much. Just stay healthy during the physiological period.