I'm not positive, hard to tell at such a young age but from the size comparisions shown (with car keys etc.) I believe it is a chihuahua. At that age though, especially if it is a long hair which that one could be they look similar to other breeds so hard to say for sure.
This is a Chihuahua within minutes of birth....our newest litter:
This is a puppy from the last litter at couple months old from the last litter we had. Their ears are droopy when first born...can perk up within a day or two...then as the ears grow they go down again before finally going up for good.
