
A molera in a Chihuahua is a soft spot on the top of the skull, where the bones haven't fully closed. This is a common feature in Chihuahuas, especially in the smaller varieties.
Most Chihuahuas are born with a molera, and it's usually closed by the time they're six months old. However, some Chihuahuas may keep their molera open into adulthood.
A molera can be a bit of a concern, as it can make the dog more prone to injury or infection. But with proper care and attention, most Chihuahuas with a molera lead happy and healthy lives.
What Is
A molera is a small opening in a puppy's head, comparable to the fontanelle in a human infant's skull.
Most canines have moleras that close up as they age, becoming solid, but some breeds, especially Chihuahuas, have moleras that never fully close.
Dogs, like most mammals, start life with a soft spot in the middle of their skulls.
This soft spot usually closes up within the first few weeks of life, but in some cases, it remains.
Unclosed moleras are most common in Chihuahuas, but they can also be seen in other toy and brachycephalic breeds.
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Causes and Symptoms
Puppies are born with their skull bones unfused, allowing for passage through the birth canal, but this hole usually closes by the time the animal is four to six weeks old.
In some dogs, this opening never closes, and it's most commonly seen in Chihuahua and Chihuahua mix dogs.
The specific head shape of a Chihuahua may alter the chances of the molera remaining open, with apple-headed Chihuahuas more likely to have an unclosed molera than deer-headed Chihuahuas.
A soft spot remains in the center of the skull where the head is soft to the touch, and this is not considered a medical abnormality in Chihuahuas.
- Skull does not fuse
- A soft spot remains in the center
Causes of Dogs
Dogs are born with their skull bones unfused, which allows for a smooth passage through the birth canal. This hole in the top of the skull usually closes by four to six weeks old.
In some dogs, this hole never closes, and it's most commonly seen in Chihuahua and Chihuahua mix dogs. This condition is occasionally seen in other small or brachycephalic breeds of dog.
Symptoms of Dogs
Dogs who retain unclosed moleras into adulthood may not show any noticeable symptoms, but a soft spot can remain in the center of the skull.
The skull does not fuse together as it normally would, leaving a soft spot in the center.
Chihuahuas are the breed most often affected by unclosed moleras, and their head shape can affect the chances of the molera remaining open.
The specific head shape of a chihuahua can influence whether the molera closes or remains open.
Here are some characteristics of the head shapes that can affect the molera:
- Apple-headed chihuahuas have a more rounded head with a 90-degree angle where the muzzle joins the forehead.
- Deer-headed chihuahuas have a longer head with a 45-degree angle where the muzzle and forehead meet.
Dogs with the apple-shaped head are more likely to have a molera that does not close than those with a deer-shaped skull.
Checking Your Chihuahua
Checking your Chihuahua for a molera can be a simple process that requires some gentle handling and attention to detail. You can feel your Chihuahua's skull for the presence of this cranial opening by following these steps.
Place your index finger at the "stop" between your Chihuahua's eyes and the top of his nose. This is a good starting point for feeling the molera.
Gently run your index finger up your Chihuahua's skull to feel for a groove or indention where the skull hasn't developed. If your Chihuahua has a molera, you should be able to feel this area.
The size and location of the molera can vary, but it's usually located in the center of the skull. You'll want to take note of where the molera is located, as you'll want to use caution to protect this area from blunt force trauma.
Some Chihuahuas may have a more rounded head, known as an apple-shaped head, which can increase the chances of a molera not closing. In these cases, the molera may be more noticeable when feeling the skull.
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Diagnosis and Treatment
Diagnosis of molera in Chihuahuas is typically straightforward and can be done with a simple physical examination.

A veterinarian can easily feel the molera by palpation, and in some cases, x-ray technology may be used to get a clearer picture of the bones in the skull.
The size and positioning of the hole can be determined through x-rays, which can provide a more detailed view of the skull bones.
In some cases, an ultrasound of the dog's head may also be performed, especially if there are other physical signs pointing to hydrocephaly.
The prognosis for most dogs with molera is excellent, and with proper care, they can live long and happy lives.
This is especially true for Chihuahuas, where molera is a common and often required feature in the breed.
Diagnosis of Dogs
Diagnosing molera in dogs is relatively straightforward and can often be done with a simple physical examination.
A veterinarian can easily feel the molera by palpation, which is a hands-on examination of the dog's body.
Additional testing may be required in certain circumstances to determine the size and positioning of the hole.
An x-ray of the dog's skull can provide a clearer picture of the bones and help determine the extent of the molera.
There is no established connection between the presence and size of a molera and the development of hydrocephaly.
In some cases, an ultrasound of the dog's head may be performed to visualize the brain and surrounding structures, particularly the ventricles.
Treatment of Dogs
Dogs with molera need extra caution to avoid brain trauma. This means being careful with activities that could cause them to jump or fall.
It's essential to exercise extra caution when dealing with dogs with soft spots, as they can be more vulnerable to damage. This includes not letting them jump down off furniture, out of your arms, or off high stairs.
You should also be selective about playtime companions, as rough handling can cause harm. Very young children may not be able to handle your pet gently, so it's best to supervise interactions closely.
Large, exuberant dogs may sometimes safely play with small dogs, but dogs with molera are particularly susceptible to bites and blows. Even during play, a blow to the head can cause serious damage.
With proper care and precautions, dogs with molera can live long and happy lives.
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Recovery and Care
Dogs with molera can live very long and happy lives with just a few precautions.
Most Chihuahua breeders no longer require soft spots as a breed standard, which is why the number of dogs with open moleras is declining.
The average size of Chihuahuas has been on the rise, but smaller dogs are still more likely to have molera.
Chihuahuas can live long and happy lives with proper care and precautions, making the prognosis for most dogs with molera excellent.
Veterinary Professionals
As a veterinarian, you play a crucial role in identifying and treating moleras in Chihuahuas. Moleras are a common condition in this breed, and early recognition is key to preventing complications.
Molera size can vary, but in most cases, it's a small opening in the skull that can be felt or seen. This opening is usually located at the top of the head, just behind the eyes.
Veterinarians should be aware that moleras can be associated with hydrocephalus, a condition where fluid accumulates in the brain. Regular check-ups and monitoring are essential to catch any signs of hydrocephalus early on.
A skilled veterinarian can diagnose a molera by feeling the skull or using imaging tests like X-rays or CT scans. These tests can help determine the size and location of the molera.
In some cases, veterinarians may recommend surgery to close the molera and prevent complications. This is usually done in puppies under 6 months old, as their skulls are still developing.
Veterinarians need to be knowledgeable about the breed-specific characteristics of Chihuahuas and the potential risks associated with moleras. By working closely with owners and staying up-to-date on the latest research, veterinarians can provide the best possible care for these adorable dogs.
Chihuahua Breed Standards
The American Kennel Club (AKC) initially required the Chihuahua breed to possess a molera in 1923.
The AKC updated its breed standards to give no preference to the molera, making it possible to compete Chihuahuas with or without this feature in conformation shows.
The Canadian Kennel Club (CKC) also gives no preference to the molera, stating that a well-rounded apple-dome skull is acceptable with or without it.
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Here's a breakdown of how different organizations view the molera in their breed standards:
The UKC and FCI view a molera as a fault, which means Chihuahuas with this feature are automatically disqualified from competition.
Chihuahua Breed Standards
Chihuahua breed standards have undergone significant changes over the years. The American Kennel Club (AKC) initially required Chihuahuas to have a molera to compete in the show ring.
The AKC updated its breed standards to give no preference to the molera. This means that Chihuahuas with or without a molera can compete in conformation shows.
The United Kennel Club (UKC) and Fédération Cynologique Internationale (FCI) view a molera as a fault, automatically disqualifying Chihuahuas with this feature.
Here's a comparison of the breed standards of leading canine organizations:
The Canadian Kennel Club (CKC) also gives no preference to the molera, aligning with the AKC's updated breed standards.
Will My Chihuahua's Hair Grow?
Chihuahuas have a unique skull structure, and one of the features that can be a concern for new owners is the molera. However, the molera is not related to hair growth.
A Chihuahua's hair growth is largely determined by genetics, and there's no specific information in the article about the breed's average hair length or growth rate.
Chihuahuas are known for their short coats, but the article doesn't provide information on how to promote or slow down hair growth in the breed.
In fact, the article doesn't mention hair growth at all, focusing instead on the molera and other breed-specific features.
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