Heat period of dogs averages five to seven days. It occurs twice a year in normal cases. But sometimes this cycle exceeds to thrice a year. There are three cycles of heat known as proestrus, estrous and diestrous. First one lasts for about five to seven days. Second one captures four to thirteen days and third one carries seven to ten days. If it is female then it is diestrous and its bleeding period lasts for almost seven to thirteen days. It also depends on the size and maturity your Chocolate Lab. A typical cycle ends in one hundred and fifty days
When My lab starts her cycle how many days after she starts her cycle is the right time to put her with the male dog for breeding.
A female black lab is in heat for at least a week and a half. If you want her pregnant mate her 9-11 days after period started.