The Chihuahua’s AKC breed standard reads, “A well rounded “apple dome” skull, with or without molera.”

Huh?

What’s a molera, and is an “apple dome” skull different from, say, a peach dome skull? First things first. The molera (also called the fontanel), is a soft spot on the top of a Chihuahua’s head not unlike a human infant’s soft spot. Back in the day, a molera was considered a mark of purity in the breed, but many Chihuahua puppies are born without a molera, probably as many as are born with one. We always defer to breed experts, but our reading suggests that the molera usually shrinks as the dog matures and ends up between nickel- and dime-sized.

As for the fruit head thing (no disrespect intended), most Chihuahuas can either be regarded as having an “apple head” or “deer head” based on how they look. Chihuahua’s with “apple heads” have a skull top that is rounded and more prominent than the rest of their skull. They also tend to have a short nose and muzzle.

Now you know.

Image from irresistiblepets.net