When does dogs come in heat?

Question
I have a 15mo. old female Min. Schnauzar that has came in heat when she was 9mos. old.  When will she come back in heat? We also have a 8mo old male Min Schnuazer

If you could help me it would be great.
Thank you
Stacey

Answer
Hi Stacey -- she should come into heat anytime.  Often a female's cycle is irregular, In average there is a five to nine month interval but some females come into heat only once a year.  Females that are slow to come into heat often will do so when allowed to run or living with a male for three to four months.  

Consideration should also be given to your demographics, the weather plays a large part. That's why females usually come in the spring and fall.  Wild dogs only come into heat in the spring when the days lengthen.