Because we breed for apple head Chihuahuas with a lovely 90 degree stop, your puppy will most likely have an open molera when he/she goes home. In our hand-outs there is an AKC sheet included that has a paragraph on the topic. Please, educate yourself about this breed conformation of your new Chihuahua. We believe an educated Chihuahua owner will have less worries and more enjoyment during the journey of owning this beloved breed. We hope every customer has a good vet that is familar with the breed characteristics. However, we encourage you to do your own research on the breed so you can feel confident in caring for your new family member. We have a extensive library of books on Chihuahuas and found most of them online through Amazon. But with the computer your education can be just as good reading accurate websites and the Chihuahua Club and AKC information on the breed. Enjoy the new learning curve and congratulations on your new puppy!
Historically, the Chihuahua developed in Mexico and the United States has displayed a “soft spot” on the top of the head. In the Chihuahua this spot, or fontanel, is known as a MOLERA; and is the same as that found in human babies. In the past, this molera was accepted as a mark of purity in the breed, and it is still mentioned in most Chihuahua breed standards the world over.
Its presence is nothing to become alarmed over.
Unfortunately, many lay people and some veterinarians not familiar with the Chihuahua have tried to link the mere presence of a molera with the condition known as hydrocephalus. This has caused many new-comers to the breed serious concern and undue worry. The truth is that a domed head with a molera present does not predispose the Chihuahua to this condition. Along with the observations of devoted breeders over the years, there is adequate medical evidence to support this statement.
In “Diseases of the Brain” 1989, Green & Braund stated that many clinically normal toy breeds may have open fontanels without associated hydrocephalus.
Walker and Rivers, Veterinarians at the University of Minnesota concluded that there did not appear to be any relationship between the presence or size of a fontanel and the condition of hydrocephalus.
Alexander de Lahunta of Cornell University in New York, one of the top neurologists in this country, stated that it would be wrong to conclude that any opening is abnormal.
While it would be impossible to list all the medical documentation here on this page, these few included here are perfectly clear; the presence of a molera does not mean the Chihuahua has a medical problem.
With or without a molera, the healthy Chihuahua that is loved and given proper veterinary care will live well into its teens as an irresistible member of the family.
PPCP Article: Understanding the Difference between Molera and Hydrocephalus (2005)
Taken from Chihuahua Club of America Page on Breed Conformation