How to bring a female dog into heat?

A female dog’s heat timing varies with constitution, environment, season and nutrition, so it is irregular. To encourage heat, first boost her nutrition and condition. Let her mix with males whose nuzzling, chasing and mounting stimulate earlier heat and ovulation. Normally she heats at 6-8 months, more often in spring (Mar-May) and autumn (Sep-Nov); if not urgent, simply wait and observe.