My mom has a Boston that seem to come in heat every four months I always thought it was six months? If the female has a litter how soon after should she come in heat?
Every 4 months is unusual but each dog is different. You count the cycles from onset to onset. In other words...if she starts her heat cycle Jan 1st then her next heat will be May 1st whether or not she had puppies. It would be possible to have a heat cycle start Jan 1st...get pregnant Jan 13th..have puppies March 17th wean the puppies by April 28th and begin another cycle just days later. If she is being bred she should only be allowed to have puppies once a year though because as you can see it can be hard on her system.
Luckily our females have their heat cycle every 7-8 months.