How often do dogs go into heat?

A female dog usually goes into heat twice a year, in spring and autumn, once around March-May and once around September-October, about 6 months apart. Males are triggered by females—when they smell a female in heat they show symptoms.

A female in heat has vaginal discharge and shows irritability, reduced appetite, more drinking, and more urination. Put a dog diaper on her and prevent male dogs from mounting when outside.