According to boredpanda.com
"Nessa, probably the tiniest cavalier puppy who is taking the internet by storm with nothing else but his cuteness. The first thing you probably notice about him, other than the beautiful eyes, is his pocket-sized body. While usually cavalier dogs weigh around 12-12lbs, the little Nessa is just 7lbs. However, his weight is not a result of genetic mutation or anything like that, in fact, he was just a runt of the litter."
Read more and see pics at boredpanda.com