What is a Molera or ‘Soft Spot’ in Chihuahuas?

What is a Chihuahua's molera?

If you rub your Chihuahua’s head and feel an opening in his skull, try not to panic. Known as a molera or “soft spot,” it’s a common anatomical feature with the breed. Research shows that approximately 80% to 90% of all Chihuahuas are born with a molera. It was once even considered a mark of purity for Chihuahuas.

After discovering your Chihuahua’s molera, you may have some questions. In this article, we’re going to cover some common topics regarding this condition, including the following:

  • An overview of moleras
  • Prevalence of moleras in Chihuahuas
  • Why Chihuahuas have moleras
  • Whether or not it’s linked to hydrocephalus
  • How to care for a Chihuahua with a molera
  • What the AKC and other Chihuahua breed standards say about the molera
  • And more

What is a Molera?

A molera is an opening in the top of a dog’s skull where the parietal and frontal bones have not fused together.

Most puppies are born with an incomplete skull, the opening of which is called a molera. It’s found at the top-center of the skull, a few inches above the nose. The molera is typically either circular or diamond shaped. It has an average size of 1/4 inch to 1 inch in diameter, making it about the size of a dime. Some have smooth edges, whereas others have rough or jagged edges. As the pup matures, cartilage pulls the skeletal plates together and calcifies the skull.

Dogs aren’t the only animals born with an incomplete skull. While not referred to as a molera — that term specifically applies to dogs — it’s a common feature in many mammals. Even human babies are born with an incomplete skull. The cranial opening in babies is known as a fontanelle.

Normally, these gaps of unfused skull bone gradually close over time. In Chihuahuas and other toy breeds, however, the molera may never close. Some Chihuahuas live their entire life with this cranial opening, in which case certain precautions should be taken to protect against injury.

Chihuahua with a molera

How Common are Moleras in Chihuahuas?

Moleras are very common in Chihuahuas, affecting roughly eight in 10 newborn pups. It’s such a common feature, in fact, that it’s mentioned in the Chihuahua breed’s standards by major canine associations throughout the world.

What’s really interesting is that moleras were even more common in Chihuahuas during the breed’s early years. Up until the early to mid-1970s, Chihuahuas were bred to be smaller, with a preferred weight of just 2 to 4 pounds. The preference for smaller Chihuahuas resulted in a higher rate of moleras.

Because of their smaller, dome-shaped skull, apple-head Chihuahuas are more likely to develop and retain a molera than their deer-head counterpart. Teacup Chihuahuas are also more likely to have a molera because they too have smaller heads.

How to Check Your Chihuahua for a Molera

Unless the molera is unusually large, it’s hard to identify by visual observation alone. A veterinarian can perform an X-ray to see if your Chihuahua has a molera, and if so, how big it is. But you can also feel your Chihuahua’s skull for the presence of this cranial opening.

Follow the steps below to check your Chihuahua for a molera:

  1. While seated, coax your Chihuahua onto your lap.
  2. Place your index finger at the “stop” between your Chihuahua’s eyes and the top of his nose.
  3. Gently run your index up your Chihuahua’s skull.
  4. If your Chihuahua has a molera, you should feel a groove or indention where the skull hasn’t developed.
  5. Take note of where the molera is located, because you’ll want to use caution to protect this area from blunt force trauma.

Chihuahua Breed Standards and Moleras

When the American Kennel Club (AKC) created the first Chihuahua standards in 1923, it required the breed to possess a molera. If a Chihuahua didn’t possess this cranial opening, he couldn’t compete in the show ring and was automatically disqualified from winning conformation awards. It wasn’t until several decades later when the AKC updated its breed standards, now giving no preference to this anatomical feature.

Here’s what the world’s leading canine organizations currently say about the Chihuahua’s molera in their breed standards:

  • American Kennel Club (AKC): “A well rounded apple-dome skull, with or without molera.”
  • United Kennel Club (UKC): “Disqualification: An open fontanel, a hole or gap in the center of the skull, referred to as a molero.
  • Canadian Kennel Club (CKC): “A well rounded apple-dome skull, with or without molera.”
  • Fédération Cynologique Internationale (FCI): “Well rounded apple head. Disqualifying faults: Dogs with an open fontanel.

To recap, the AKC and CKC Chihuahua breed standards give no preference to the molera, meaning you can compete Chis with or without a molera in conformation shows. The UKC and FCI, however, view this anatomical feature as a fault, meaning Chihuahuas are automatically disqualified if they possess a molera.

Why Do Chihuahuas Have Moleras?

Chihuahuas have moleras for the same reason human babies have fontanelles: It allows for easier passage of the head through the birth canal.

Because of the breed’s large head and small pelvis, female Chihuahuas often struggle to give birth. The molera, however, helps by allowing the pup’s head to temporarily flex and squeeze through the birth canal.

Will My Chihuahua’s Molera Close?

A Chihuahua with a molera

There’s no way of knowing when or even if your Chihuahua’s molera will close. Statistics show that moleras fully close in about half of all Chihuahuas born with this anatomical feature.

Normally, a pup’s skull gradually fuses together as he matures. However, it may take anywhere from three months to three years for the molera to fully close — or it may never close. If a Chihuahua’s molera doesn’t fully close, it will likely shrink in size as cartilage pushes the parietal and frontal skeletal plates together.

Is a Molera Harmful?

In the past, it was believed that dogs with a molera had a higher risk of developing hydrocephalus, a serious medical condition in which cerebral spinal fluid (CSF) accumulates in the brain. Instead of draining, fluid builds up and soaks the ventricles of the brain, causing the brain to swell. The increased pressure caused by hydrocephalus can lead to brain damage, seizure, coma or death.

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. 

Other breeders and experts refute these claims. Many Chihuahuas that suffer from hydrocephalus do, in fact, have a molera. But moleras are common in Chihuahuas, and not all Chihuahuas with this cranial opening suffer from hydrocephalus. More research is needed to conclusively determine whether moleras play a role in hydrocephalus.

A molera may or may not predispose your Chihuahua to hydrocephalus or other diseases, but you should still take precautions to protect your Chi’s head from injury. Without a fully developed skull, your Chihuahua may sustain brain injury from trauma to the head. Until it closes, follow the tips below to protect your Chi from injury.

Tips to Protect Your Chihuahua From Molera-Related Injury:

  • Let your veterinarian know about your Chihuahua’s molera.
  • Don’t allow your Chihuahua to jump on and off furniture (consider using pet stairs instead).
  • Watch your feet to avoid accidentally kicking your Chihuahua in the head.
  • Supervise your Chihuahua during playtime.
  • If your Chihuahua is epileptic — for reasons not associated with the presence of a molera — hold him during seizure episodes to prevent injury.
  • Use minimal pressure when petting your Chihuahua’s head.
  • If your Chihuahua hits his head and begins acting unusual — lethargy, trouble breathing, agitation, seizure — take him to the vet immediately.

The presence of a molera isn’t something that Chihuahua owners should lose sleep over. It’s a completely normal anatomical feature that usually closes over time. Most Chihuahuas are born with a molera because it allows them to pass through the birth canal with greater ease. As newborn Chihuahuas age, this cranial gap will begin to close. Even if doesn’t fully close, there’s no evidence linking the molera to any adverse health condition.

Does your Chihuahua have a molera? Let us know in the comments section below!

References:

http://www.chihuahuaclubofamerica.org/images/purina-pdfs/Purina-Differences-Between-a-Molera-and-Hydrocephalus.pdf

https://www.vetary.com/dog/condition/molera

Comments

    • Debbie
    • August 21, 2022
    Reply

    I have a 8-year-old small 2 and 1/2 lb Chihuahua and at night she’ll start scratching toward her ears with her front paws and then with her back paws causing a seizure. She has two very soft spots on each side of her head. Got any idea what that is?

    • Kathy Briley
    • August 23, 2021
    Reply

    Yes my 10 week old chihuahua has one.

    • Grace Mae Ritter
    • October 19, 2020
    Reply

    I rescued an 8 year old chihuahua last year. I knew nothing about the breed, so when I felt her head, I was shocked! What was this dent in her skull? Luckily she is as feisty as any other chihuahua, but she has a lot of health issues both autoimmune and due to the neglect in the years before I adopted her. She is also blue, which I read is rare in chihuahuas (but probably also contributes to her health issues). Oh well. She is also toothless and has metal knees (she had horrible periodontal disease and luxating patellas). She is my bionic girl!

      • Jackie Barnett
      • January 19, 2021
      Reply

      I just found out all about this by doing my own research. Yes my Tiny has a small diamond shaped one.

    • Liz
    • October 11, 2020
    Reply

    I had a beautiful girl for 10 yrs a white dear head chi with a molera. One night she had a seizure, first ever I rushed her to the hospital they couldn’t stop the seizure and said it was intercranial pressure. She had been with me all day no idea what caused this. My vet never said this could happen. Do these things just occur randomly? She was 3 lbs it was horrifying.

    • Christina mytckak
    • October 22, 2019
    Reply

    What if the scalp also isn’t together like a slit

      • Kelsey
      • October 14, 2022
      Reply

      My chihuahua is just a bit over a year now, and though she isn’t a teacup, she weighs just about 3 pounds. She most likely was the runt, as her sister from the same litter is 10 pounds. She has a molera and it’s always made me worry since it hasn’t closed yet even though it has gotten smaller. This article gave me some peace even though seeing some of the comments has also gotten me worried. It’s so scary leaving her at home when I go to work and can’t watch her 24/7, but she’s always been healthy and a smart pup so I wish her as many years with me as possible.

    • Alex
    • October 12, 2019
    Reply

    My chihuahua of 6 years just died because he fell backwards and hit his head right on the soft spot. He died instantly. My wife and I are traumatized and shocked. We loved him so much and took incredibly good care of him since he was a puppy. I will miss him the rest of my life. Please know getting a chi with a soft spot, please understand that years can go by and nothing will happen and something so sudden as this and he’s gone even if you are so careful as we were. All it takes is falling once. It’s absolutely terrible and agonizing to lose a best friend and in such a way. He was amazing. I’m sorry but I’m still grieving and in tremendous pain for his loss.

      • Stephanie
      • July 17, 2022
      Reply

      Same thing happened to me the other day with my baby. He had just turned 10. He fell off the bed and hit his head and died within minutes of it happening. I tried to give him mouth to mouth but I couldn’t bring him back. I am beyond devastated.

    • Pamela R
    • October 9, 2018
    Reply

    My three year old Chihuahua is a teacup (3 pound)apple head with a fairly large molera – about 4/5 inch by 3/8 inch diamond shaped. I am cautious about play with larger dogs and not to drop him, but he is as intelligent and healthy as can be.

      • Brittney DiBetta
      • August 20, 2020
      Reply

      Thank you for eating my mind!

        • Olden McGroin
        • February 14, 2022
        Reply

        You’re welcome. It was DELICIOUS!

    • Jacquelyn
    • September 17, 2018
    Reply

    My Chi has one also. My Vet told me during his first visit. That was the first time I ever heard of it and I have been monitoring it all along. It is definitely shrinking. He is 5 1/2 months old now and it has gotten smaller but still there. It’s roughly diamond shaped and about 3/8 of an inch at the widest which seems big.
    He seems to be in perfect health but I am more concerned about him then I would be otherwise and don’t let him play with other dogs except for his 10-year-old big sister, a Yorkie Who is very gentle with him.
    I’m afraid an innocent play bite could slip a tooth in there and kill him unintentionally .
    He has stairs going up to furniture because he is little. Having a Yorkie I know it’s bad for their knees to be jumping off furniture .
    The vet told me it may not close completely but I’m still hoping it will.
    I looked into helmets but with those upright years I don’t know how they would work so I’m thinking about designing a thick leather cap that would strap under his chin. He wears sweaters a lot so maybe he would tolerate something on his head.
    Thanks for the article. I found it very informative and interesting.

      • Pat
      • September 20, 2018
      Reply

      My newly purchased 5 month old Chihuahua has a Molera, and I was advised by my vet that it probably won’t close if it hasn’t by now.

      • Muncy wolgast
      • April 26, 2019
      Reply

      Since he wears clothes try him in a hoodie with the area padded.

    • Cynthia Salyers
    • July 6, 2018
    Reply

    My chihuahua has a diamond shaped molera on her skull, she is almost 2yrs old and it is closing some, but it still hasn’t fused completely. She is very smart and is almost finished with her service dog training. The molera doesn’t hinder her activities at all.

      • Kaja
      • August 16, 2019
      Reply

      Cynthia, thx for your comment. I just got a small chi, that I’m fostering for the moment, coz not sure how my elderly chi will accept him. He has an open fontenelle too, is nearly 4mnths old. I pray it closes soon. The vet said in 2-3 weeks.
      Great that your chi is a service dog. In what field? Maybe I could have mine to do the same, later. Thank you. Take care of your dear chi!

      • Beth Walker
      • February 26, 2020
      Reply

      My puppy has one too. I just found out yesterday. I really was wanting to train her as a service dog as she seems smart too.
      Can you tell me how to start the training?

    • Rachel Bolton
    • May 26, 2018
    Reply

    Just adopted a 8 week old Chihuahua and found out she has a fairly large molera . vet told me it probably will not close. I was so stressed about it until I read this article. Thank you !

    • Jennifer
    • April 26, 2018
    Reply

    I have an 8 month old Chi and he has a very large molera with bulging eyes that cause him to have to turn his body to look at me. He walks in left handed circles all day long and this is how he gets from place to place. He has recently developed a small “pimple” like spot above his eyebrow. He does not behave like he is in pain. Could this be because he has fluid on the brain?

    • Raina Hay
    • April 22, 2018
    Reply

    I was given an eight week old chihuahua mix recently. When I saw the little fella for the first time at six weeks he was trying to play but being dominated by his litter mates because of his tiny size. Upon receiving him I took him to the vet because he was not eating and barely moving around. The vet wanted to put him down because he had an oversized molera and that he would have hydrocephalus. I refused and wanted to give him a chance. I was sent home with a can of proplan plus food and rebound supplement. He ate some of the food the first day and will take the supplement if given with a syringe. This is day 2 of me having him and I am unable to get him to eat and have to forcefully give him the supplement. He will leave his bed to go potty but either goes right back or will scratch at his head then put It down and move like his is lost. Recently he has taken to retching up about ten minutes after I give him the supplement. I hate to give up on the little fella but am I kidding myself that he will survive? Am I causing him undue pain? Should I have him put down?

      • Dave
      • May 3, 2019
      Reply

      Hope you haven’t given up, & he is still with us..?

      • Chihuahua mummy
      • May 17, 2020
      Reply

      Hi
      Sometimes the best thing is to do what feels wrong.😪 If he is tired then love him and let him go. He will never be forgotten and will know that he was loved. I had a similar Chihuahua puppy his mum pushed him away because she knew he was poorly. He was having small seizures and was going in wobbly circles all the time I fed him cleaned him and comforted him with a hot water bottle. When I fed him he would bring most of the puppy milk straight back up. It broke my heart to see him struggle along. The vet told me to let him go as i had other healthy pups. I couldn’t … wouldnt ..but then I realised it was my pain that was keeping him alive and he had fought so hard and it was time to let him sleep. My heart goes out to you 💌

      • Chihuahua mummy
      • May 17, 2020
      Reply

      Hi
      Sometimes the best thing is to do what feels wrong.😪 If he is tired then love him and let him go. He will never be forgotten and will know that he was loved. I had a similar Chihuahua puppy his mum pushed him away because she knew he was poorly. He was having small seizures and was going in wobbly circles all the time I fed him cleaned him and comforted him with a hot water bottle. When I fed him he would bring most of the puppy milk straight back up. It broke my heart to see him struggle along. The vet told me to let him go as i had other healthy pups. I couldn’t … wouldn’t ..but then I realized it was my pain that was keeping him alive and he had fought so hard and it was time to let him sleep. My heart goes out to you 💌

    • Tania
    • December 20, 2017
    Reply

    My 6 months old chi also has this molera, im afraid that it wont close when he grows up.

    • Martine
    • October 21, 2017
    Reply

    Who knew!! I have shown and bred dogs for many years. Got this pet chihuahua and my 14 year old discovered his soft spot.

    I told my husband that we need to get him a little doggy helmet.

      • Rachel Bolton
      • May 26, 2018
      Reply

      I thought about a helmet too!

        • Hayley Urbanski
        • April 23, 2021
        Reply

        Were to gt helmet??? Pls

    • Suzanne
    • October 8, 2017
    Reply

    Hi yes my 10 week old chi does have a soft spot/indent I’m hoping it will close as he gets older

    • Oana
    • September 27, 2017
    Reply

    Hello, my name is Oana and I have a apple head toy chihuahua called Yoda. I Love him so much and now I am so desperate. Yoda is 2 years and a half and few months ago he started to have some pain crises which indicated something in his stomach (or related to that area) with the pain appearing each 5-6 days, after he pee and pooh in the morning. He has molera (the open spot) and here in Romania the doctors told me is an abnormality (they never saw that in a 2 years dog etc.) I made him all the medical tests (except RMN) and he has same modification only on his liver and i treat him now for that. But the crises and the pain every 5 days is still there. What can I do more for him, because the doctors here they tell me is because of the head (molera, fontanel) but I don’t believe it cause he doesn’t have and liquid in his head like hydrocephalus.

      • Jacquelyn
      • September 17, 2018
      Reply

      I believe you are correct that has nothing to do with his soft spot on his head. Maybe find another vet and read as much information as you can find. My vet immediately checked his head for the soft spot. She said it is very common with Chihuahua’s.

      • Martie
      • July 14, 2020
      Reply

      I had a Chihuahua that would wake me up screaming, it went off & on for a couple months, I started making her chicken & rice soup & had no problem.. I did put her in a grain free chicken & rice dog food & she never had problems again.. If she looked like she wasn’t feeling well, I made her chicken & rice soup & she would be back to normal in now time..

      • Hayleyurbanski James Urbanski
      • April 23, 2021
      Reply

      No mine is not tired hes lovly just his head?

      • Diane Thompson
      • March 26, 2023
      Reply

      I have an 11yr old with a molera. She is very healthy. My 9 yr old does not have one and is not so good in health.

    • Miriam Fernandez
    • September 27, 2017
    Reply

    This was very informative and helpful the questions & concerns I had.

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