Size and Heat

Question
I have a 5 month old lab who weighs about 30 lbs. Is she under weight for her age? and how big do you think she'll get? Also, when do female dogs go into heat?

Answer
That sounds about like my 8 month old Holly.  She is a lean 36 pounds and 20'' at the shoulder now, and will not be getting that much larger.  Weight is a poor way to judge a dog's condition.  Go to http://www.puppychow.com/products/popup_body_condition.aspx  Evaluate her and adjust her food as needed to reach her ideal body condition.  I would also switch to an adult chow.  It slows growth allowing more time to develop strong joints.  Along with keeping the dog lean, it is the best thing to do now to avoid joint problems.  

Females usually come in heat at about 8-10 months.  There is no good reason not to spay her any time now and avoid the whole hassle.  I hope you weren't planning on adding to our problems by breeding her. It is not an easy way to make a little extra money.