My chihuahua Foxy is a year and a half now and since she was about 6-8 months old her tongue has hung out of her mouth even while it's closed.. LOL it is too cute!
Turns out she has a bit of an overbite and the vet thinks it might be that and a combination of that and her tongue being to long for her little short face
She is a tiny girl, only about 6-8" tall and about 4 pounds (she is a tad overweight, like maybe a pound). She has that apply shaped head I think, with the short muzzle (see pic)... But when she licks, that tongue is so dang long..LOL..
It always sticks out on the right side... she is a cutie and a great little dog. So easy to train to a litter box too. She is a long haired.. I have had several people ask me what breed she was..LMAO.. and then I get a funny look when I say purebred chihuahua