How many missions until D-Dog grows up?

Question

How many missions until dog grows up? I had to go back to extract but I have done missions 1-10 so far and still hasn't grown.

Answer 1

After extracting D-Dog, you need to complete six more story missions (replays count) before he grows up. You must also have completed at least three of the missions between mission 7 though mission 10 (inclusive), which count toward the six missions you need. (Source)