I have a boston terrier pit bull mix and she is currently 4 almost 5 months old and is around 17-20 pounds, she's an adoption dog so I don't know what the parents looked like they had a picture of the mother and she was about 40pounds and that was the boston terrier.

My experience is that she won't get as big as her mother. Dogs do seem to be quite inconsistent about how much more they grow after different ages. Very few double in weight at 5 months.

Weight is often misleading. I had my 4 month old Lab with me yesterday while I was out ringing bells for the Salvation Army. She is a lean 33 pounds. I had the usual couple people tell me about the 90 pound Lab they have. Very few Labs should weigh 90 pounds. Most of them would live longer lives if they were 70-80 pound Labs. See LongLiveYourDog.com - Life Span Study - Rate Your Dog

I thought boston terriers don't get big ? Twinkel