Dingo, who is dark red with with brown eyes, is the puppy who says "I'm excited too! I can't wait to get a human, and can chew on their socks!" He was the first puppy to be adopted by a young boy and his father.
Screenshots of Dingo
Besides the first screenshot, the other three may or may not be Dingo. But it's a fact that Dingo's fur is dark red, and has brown eyes. While the last screenshot shows Dingo in a lighter color, that's simply an error. Up until this frame, his fur was the correct color. The red-faced pup (which is the only other dark red pup) is on Balto's back in this scene.
There are also claims that Dingo is the Aleu clone, but that is false. The Aleu clone IS one of the six puppies, but due to inconstancies, the red bar wasn't always added to its face. This puppy also appears in the box after Dingo was adopted, so the puppy is not Dingo.