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What is Open Fontanel?

In many cases, open fontanelles in dogs may be a sign of a condition called hydrocephalus, or an abnormal cerebrospinal fluid accumulation in the brain. Many believe that the increased pressure from this accumulation can cause the holes in the skull.  Hydrocephalus can be acquired or genetic, and can be a fatal condition. While it is often seen with open fontanelles in dogs, there are many cases of the presence of these skull holes without hydrocephalus.

Open fontanelles are holes in the skull that result from incomplete closures of the skull’s soft spots during normal growth in puppies. While for many dogs these soft spots close completely by 9 to 12 weeks of age, various smaller breeds of dogs, including toy and tea cups breeds, retain these holes past puppyhood. For Chihuahuas, the open fontanelles are considered a breed standard and are called moleras. For other dogs, they can be a symptom of a serious problem.

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Symptoms of Open Fontanel in Dogs

The main symptom of an open fontanel is a soft spot or hole in the skull that remains into adulthood in a dog. For many dogs, these open fontanelles will cause no problems, but can result in injuries if subject to trauma. For other dogs, open fontanelles can be a sign of a bigger problem, such as hydrocephalus. Signs your dog may be experiencing this condition can include:

  • Presence of soft spots or holes in skull, usually located on the top of the head
  • Round, domed, or apple-shaped skull
  • Eyes directed downwards or upwards
  • Head pressing
  • Difficulties with housetraining
  • Puppies slow to grow
  • Restlessness
  • Aimless wandering
  • Lack of coordination
  • Blindness 
  • Seizures

Causes of Open Fontanel in Dogs

Open fontanelles are often a congenital defect, but it can be an acquired condition due to a problem that puts pressure on the skull and cause it to be unable to fuse completely. Reasons for open fontanelles to occur include:

  • Genetic defect
  • Hydrocephalus
  • Swelling or infection of the brain
  • Brain tumor
  • Disease process that blocks cerebrospinal fluid drainage

Breeds commonly affected with open fontanelles include many toy breeds and short faced, or brachycephalic breeds, such as: 

  • Chihuahuas 
  • Miniature Dachshunds 
  • Pomeranians
  • Shih Tzus
  • Yorkshire Terriers 
  • Maltese
  • English Bulldogs 
  • Lhasa Apsos
  • Boston Terriers 
  • Cairn Terriers 
  • Pugs
  • Pekingese 
  • Toy Poodles

Diagnosis of Open Fontanel in Dogs

If you’ve noticed a domed or apple-shaped appearance to your dog’s skull, or have felt soft spots past puppyhood, you should talk with your veterinarian. The sooner you seek medical advice, the better it may be for your dog. Be sure to inform your vet about any symptoms you may have seen. 

Your veterinarian will examine your dog and ask questions about any behavioral or neurological abnormalities. Imaging techniques can show the presence of an open fontanel, fluid accumulation, tumors, or other abnormalities, and can include X-rays, ultrasounds, CT scans or MRIs. Results from these tests can confirm the presence of an open fontanel, as well as a condition such as hydrocephalus.

Treatment of Open Fontanel in Dogs

For some dogs, the presence of an open fontanel requires no treatment, but may necessitate some special handling. Often, these dogs are adopted into families without other animals or even children, with instructions to avoid any traumas to the head. While it may resolve in puppies, an open fontanel will remain with an adult dog throughout his entire life. For those dogs who have associated or concurrent problems, such as hydrocephalus, treatment is usually needed. 


If caught early, hydrocephalus is treated with medication to reduce both brain inflammation, such as with corticosteroids, and the amount of cerebrospinal fluid produced, often with omeprazole. More severe cases may also need anti-seizure medications, diuretics to reduce fluid production, and electrolytes.


For a more permanent solution, a ventriculoperitoneal shunt can be placed. This is a small tube surgically implanted into a ventricle of the brain to take the excess cerebrospinal fluid and safely drain it to another part of the body. As your dog grows, additional surgeries are often required to re-fit the shunt. Complications of this procedure include infections, and over or under drainage. The success rate for a shunt is approximately 80%. While this procedure can help a case of hydrocephalus from worsening, it does not resolve the open fontanel itself.

Recovery of Open Fontanel in Dogs

Recovery of an open fontanel in your dog will depend on the severity of his condition. If your dog has an open fontanel, but no other medical issues, then he can live a long and healthy life, so long as he receives no direct trauma to that area. If your dog’s condition is more severe, with associated hydrocephalus, treatment can help to resolve symptoms. While symptoms in some dogs may resolve in two years, other cases may need repeated treatments of medications or surgery to place or re-fit a shunt. You may need to administer medications or postoperative care to your dog at home, and ensure a safe and trauma free environment throughout his lifetime. 

Prevent open fontanelles and hydrocephalus in future generations by refraining from breeding affected dogs. If you have a breed of dog which is known for these conditions, monitor your puppy’s growth and seek advice from your veterinarian if you notice any of the associated symptoms.

Open Fontanel Questions and Advice from Veterinary Professionals

12 Weeks
Fair condition
3 found helpful
Fair condition

Has Symptoms


Hi!😊 I have a 12-13 months old Chihuahua puppy at home and I am scared that he can hit his soft spot. In general he is a quite jumpy and happy dog which is super cute but it doesn't make it easier or makes it less scary when he comes really close to the wall etc.😐 He has quite good coordination and he walks, runs and jumps normally. How can I tell if he hit it? And any tips of preventing it besides when playing a little to sit at the door to cover the pointy edge? Thanks in advance for the help!😊

Today I noticed my puppies head has a soft spot on her head feels like her skull is open she’s her normal self should I be worried her head wasn’t this way yesterday

Hi I have a Puppy of 50 days she is a yorkie/shinzu right now is like in pain she cant poop properly and when i pet her head she had in her skull on top a sorta like a hole, she is very playful and yappy but today in the morning she was wasn't I'm worried what should i do?

hi there, i have been a breeder for 54 years, and for a chihuahua to have that is generally called a Morela which is not abnormal as they have apple heads. And yes, they have more hydrocephalus as well. But if he is normal and well he ought to live a long and healthy life. The likelihood of him hitting his head is slim. Just steps at couch and bed etc. Also, when I cook, I tell the dogs they have to sit back so I can't drop anything on them.

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Tinker Belle
11 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Aimless routine pacing in a pattern

I just rescued this baby. I thought at first it was anxiety then I noticed a pattern. She can do the routine pacing in the same route for over 30 minutes. She does have an open Fontanel which I know is normal in these breeds. Is there anything I can do for her or medicine to help her relax. Some days mild and others more often.

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1 Month
Mild condition
0 found helpful
Mild condition

Has Symptoms

Stomach Pain
Troublem pooping
Skull feels to have a hole

Hi My dog is just a little puppy and well when we got her, she was 47 days old well anyway today my little Luwa couldn't poop like as if something was stuck in her, the other thing was when i petted her head she skull felt like there was a hole and well the other thing was that her stomach wasn't normal i dont know what to do could you help me

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Chihuahua Papillion mix
1 Year
Serious condition
0 found helpful
Serious condition

Has Symptoms

pain when hitting the top of head


I have a Papillion Chihuahua mix that has fontanelle. My 1 year old dog has hit his head several times and whaled and cried uncontrollably from the pain. I'm extremely frightened at this and want to do what I can to make his life as normal as possible. Is it possible to do a bone graft to cover it? and what are the health risks of surgery?

My Chion has a fontanelle. I use steps for the couch and bed for her. I hope yours is ok. They are such great and smart dogs!!!

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Boston Terrier
1 Month
Mild condition
0 found helpful
Mild condition

Has Symptoms

Seizures, Soft spot, Slow Growth

I got this little baby a month ago when my boston terrier gave birth. Well this little nugget is having a seizures, have a soft spot on its head like an apple and she have a hard time walking like she is funny in that way but at the same time, you can see she has a hard time walking. She's also grow slow and easily lost her weight, I'm afraid she have a hydrocephalus,now she's only a haft of her brothers body. I didn't let her visit a vet after a month because I'm afraid and I don't have money. Could it be a Hydrocephalus?

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French Bulldog
9 Weeks
Fair condition
0 found helpful
Fair condition

Has Symptoms


I have a 9 week old french bulldog and she was the runt and the vet said she had an open fontanel and she is very busy (paces and runs) not sure if this is just puppy activeness or something else. Have our vet visit next week.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
At nine weeks it can be difficult to distinguish erratic puppy behaviour from something pathological, an open fontanel means that the skull hasn’t closed and doesn’t always lead to other conditions (hydrocephalus etc…). You should keep a close eye on Trixie for the time being and visit your Veterinarian regularly to monitor for any other signs or symptoms. Regards Dr Callum Turner DVM

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Chihuahua, poodle
4 Months
Fair condition
0 found helpful
Fair condition

Has Symptoms

open fontanel

hi i am looking to purchase a puppy we have found one that is 4months old chihuahua cross poodle (I have 2 young children 4 and 8) puppy has open fontanel and can be seen to be unsteady on its feet do you think this is a sign if hydrocephulas and would this puppy be suited to our home concerned that I may end up with lots of vets bills and ongoing problems including puppy not living very long

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
The presence of molera (fontanelle) on a pup doesn’t necessarily mean that this pup will be affected by hydrocephalus but if there are symptoms of being unsteady on the paws or any other concerning symptoms I would avoid purchasing the puppy. I cannot give you any assurances that Toto will be worry free or wouldn’t require regular veterinary care. Regards Dr Callum Turner DVM

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York Shire terrier
5 Months
Fair condition
2 found helpful
Fair condition

My yorkie puppy is 5 months old with open fontanel. He's healthy and isn't giving him any problems. I was just wondering if there is something I could be giving him to help it to close?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
By five months of age the fontanel should be closed and if it isn’t closed already it never will; there are some conditions like hydrocephalus which would cause the fontanel to remain open and affect dogs should be neutered so that the problem isn’t passed on. You should speak with your Veterinarian about this condition as well as looking into protect for Tucker whilst playing outside. Regards Dr Callum Turner DVM

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