how old is my brothers dog?

Question
My brother was driving on river road on his way back houme from Hermiston, Oregon. He found a female Pitbull. she was aboused (i dont know if i spelled that right i am only 12)? Anyway he found her about a year ago and when zach, my brother, broght her home he said that "you can tell that she has already had pups." and now she bairlly has some white hairs bellow her nose, abviouslly on her upper lip. And i was wondering if any one could tell me how old she is?

Answer
The only way to really guess is by looking at the teeth,as some dogs get grey/white hairs at a young age,but even then it is hard to tell,at some dogs wear them down by chewing on chains and or rocks

So the best way to tell is to ask your vet,and he/she will guess by looking at the teeth,as well as the general condition of the dog