Soap had found you during one of the missions, you were a small dog, which could be great for training. He considered taking you to Price.

“I’ll be right back” He tells Ghost, walking over to the bushes where you lay. “Hey buddy?” He pets your fur

He loved animals. Price and Ghost were constantly telling him to stay away from wild one because they could get him sick but he didn’t care, if he saw something he liked, he was gonna get it.