how to determine the age of my rescue dog

Question
I recently adopted a young large breed dog from a canine rescue. They told me he is full grown and between one and two years old. I believe he is a retriever/rotti mix.

I have owned him now for a month and a half and he is definitely still growing- right now he weighs around 65 lbs. Also I have discovered his adult teeth haven't completely grown in. His paws are slightly larger in proportion to his body and his behavior is very much puppy like.(and he looks like a large pup)

While I assume he will continue to grow, I am curious to know how old he is. Is there a way to tell by looking at his teeth? They appear to be mostly grown in, but there are two small teeth emerging from behind each of his canines on his lower jaw.

Answer
The larger the dog, the longer they grow.  I think they all have their adult teeth by 6-7 months.  I would say your vet may be the best one to estimate the age.  The vet will want to in order to give the correct treatment.  Even if the rescue had him checked, it would be good to have your own vet check him.  If the small teeth don't fall out before long, the vet mayneed top remove them.  In many parts of the country. dogs need to be on heartworm remedy year around.  

If he is less than a year old and you have him on adult chow, that is fine leading to slower growth and stronger joints.  For the same reason, you need to keep him lean.  Your dog definitely should be narrower at the waist than the hips and chest. You should be able to easily feel the ribs, but not see them. Each dog is different. Standard recommendations are a good place to start, but each dog must have its food and exercise adjusted to its individual needs. Here is a link to a good illustrated guide, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx