When does a Norwich terrier go into heat?

A Norwich Terrier typically goes into heat for the first time around six months of age, though this can vary slightly among individual dogs. The heat cycle, or estrus, usually occurs twice a year and lasts about 2 to 3 weeks. During this time, the female may exhibit behavioral changes and physical signs, such as swelling of the vulva and discharge. It's important for owners to monitor their dog during this period for her health and safety.