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Fontanel, or Molera, or Open Font, or Soft Spot

The fontanel, often known as the "open font," is something that is not uncommon in small dogs.  Within reason, this is perfectly harmless . 


I have chosen the Chihuahua as an example for my comments since the Chihuahua people are the most experienced with the fontanel.  (My personal comments on this page are always in green font.)


As many are aware, the Chihuahua breed has the open font as an allowable part of the breed standard, per AKC.  This follows suit since this is the smallest known dog breed.  Curiously enough, the Chihuahua is also among the longest living dog breeds!  Thus, how could an open font be harmful?

To quote the Chihuahua Club of America, who are the most experienced breed club regarding open fonts due to the small size of their chosen breed,

in reference to the "molera," or open font:

"Unfortunately, many lay people and some veterinarians not familiar with the Chihuahua (and other small dogs who are prone to having an open font) have tried to link the mere presence of a molera (open font) 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 (open font) present does not predispose the Chihuahua (or any other toy breed / small dog) 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.

Drs. 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.

Dr. 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.

(See "Faculty Legends: Alexander de Lahunta" -


...and "Internationally Known Scientist Recognized by Cornell College of Veterinary Medicine" -

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 (open font) does not mean the Chihuahua (or any toy breed / small dog) has a medical problem.

The Chihuahua is a little dog! They belong in the house, at their owner's side, receiving all the love they deserve to receive. With or without a molera (open font), the healthy Chihuahua (or any toy breed / small dog) that is loved and given proper veterinary care will live well into its teens as an irresistible member of the family."

Additionally, virtually all parents are familiar with the open font, or "soft spot" their children are born with.  This in no way puts their babies in danger.  There is a tough membrane protecting the brain from harm.  It would take a significant accident with the force being applied to that specific spot in order to credit the injury to the fact that they have a soft spot.  (Generally, if the soft spot is BULGING there is cause for concern.)  Of course, you wouldn't want to poke and prod this soft spot, but what logical reason could anyone have to do so?

Speaking from experience, with several children who were born early but still were able to come home after one day, their "soft spot" may have taken a bit longer close, just as the muscle layer where their umbilical cord was attached took longer to close, resulting in an umbilical "hernia."  These children had no issues whatsoever from these situations.  There was no concern regarding hydrocephalus,

and no concern regarding surgery. 


These conditions are very similar in puppies, with the results being totally innocuous the overwhelming majority of the time.

However, don't take my word for it!  Take the word of:

Drs. Walker and Rivers, Veterinarians at the University of Minnesota

Dr. Alexander de Lahunta of Cornell University in New York, one of the top neurologists in this country well as the authors of...

"Diseases of the Brain" 1989, Green & Braund


 "A 1989 Greene Braund study titled "Diseases of the Brain," however, found no association between moleras and hydrocephalus in toy breeds such as the Chihuahua. Researchers concluded that the presence of a molera does not increase the risk of hydrocephalus. A separate study conducted by Dr. Walker and Dr. Rivers at the University of Minnesota also found no correlation between the presence or size or a molera and hydrocephalus.

The presence of a molera isn't something that Chihuahua owners should lose sleep over. It's completely normal anatomical feature that usually closes over time. Even if doesn't close, there's no evidence linking the molera

to any adverse health condition."


Open Fontanel

Written by: Cindy Fern-King

"Some puppies are born with what is called an "open fontanel.” The fontanel is the location on the top of the skull where all of the skull plates join. It is equivalent to the soft spot at the top center of a human baby's head. When puppies are born, the bony plates of the skull are somewhat soft and separated. As he grows, these bones will become more rigid and will gradually fuse together. It can take two to six months for the skull plates to fuse and the soft spot (fontanel) to close....

In some breeds, such as the Chihuahua, this open fontanel or molera is actually desired....

It should be noted that even if the fontanel never closes, the affected pup can still live a full, energetic and active life....

It is mistakenly assumed that because a Maltese has an open fontanel, he will also have hydrocephalus (water on the brain). While puppies with hydrocephalus will commonly have an open fontanel due to the swelling of the brain, this is not necessarily an indication the puppy will have hydrocephalus."


"...I do know that since Amigo appeared neurologically normal there was nothing else we needed to do. If he ever showed signs of hydrocephalus, an ultrasound of the brain could be done via the fontanel, but he has a perfectly good chance of leading a perfectly normal life and never having any problems. I advised his owner to take extra care with his head and to never press the soft spot (which was the size of nickle - this is large IMHO...and is it not simply common sense not to apply pressure to head in any location?). If she wanted, there were even places she could purchase a tiny helmet for him. I wondered if Amigo would tolerate such headgear. Then I thought how cute he would look and imagined myself toting around a four-pound dog wearing a mini-bike helmet. That could be as cool as having an Irish wolfhound."

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