Heat cycles

Question
Hi,
My Yorkshire terrier went into heat August 2008, she got pregnant last week of October 2008 and gave birth 12/30/08 to 4 puppies. It is now January 28th and she is in heat again.  First questions: I didn't think dogs could get pregnant unless they are in heat? 2) Could she have been in a silent heat 2 months after her regular heat? 3) Would she go into heat while nursing puppies or would it be 6 months after having puppies?
Thank you.

Answer
Shari,

There can be a lot of reasons for a female to have erratic heat cycles.  They normally have a heat and then do not have another for at least six months.  It is possible that your female has a hormone imbalance and needs to be seen by a vet.  Hopefully with a simple injection her heat cycle will become more consistent.