color on my boxer puppy

Question
my boxer puppy is 4 months old , him concern about his color.. he has a very light black coat on his back ... is this normal ?? tihis means that he`s not pure breed??

Answer
Some fawn puppies with deep pigment do have a 'shadow' of black on their back, especially along the spine.  This will disappear as the dog ages.  If it stays into adulthood, or if it's more of a 'saddle' pattern, then there may well be another breed in the mix, as the Boxer doesn't carry the gene for saddle or black-and-tan coloring.