You Make The Diagnosis: Chihuahua Congenital Defects

During their first examination, I check puppies for congenital defects.  What is the most common congenital defect observed in Chihuahuas?  Will it correct over time?  Is it associated with any other medical problems? 


Answer:  Open Fontanelle (Soft Spot)

Open fontanelle's occur when the bones of the skull fail to meet and fuse.  I usually find them on the pup's forehead.  Most will close with time and are considered normal for the breed.  If the soft spot is large, I worry about the puppy developing hydrocephalus.  Hydrocephalus, which loosely translated means 'water brain' is an excessive accumulation of fluid within the skull.  Pressure from the fluid interferes with normal brain function and may cause severe neurologic disease.  If your puppy has a soft spot, be careful.  Since there is no bone to protect the brain, trauma to this area may cause serious neurological problems.

Unfortunately, open fontanelles are often consider acceptable to some breeders.  The beautiful puppy in the photo did not suffer from this condition.  I posted Bella's picture because she is one of the healthiest and most well behaved Chihuahua's I have ever had the privilege to examine.     

In addition to open fontanelles, I also check for several other congenital defects including cleft palates, umbilical hernias, heart murmurs and anal defects.  A common problem in all toy breeds is medial patella luxations.  In this condition, the pup's knee cap rests out of the joint, on the inner side of the knee.  These pups often require surgical repair when they are older. 

For more information on congenital defects in other breeds of dogs, please see my upcoming post titled "Congenital Defects In Puppies".

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  • 1/9/2009 11:46 PM graeme wrote:
    What would be the age of a chihuahua for me to recognize that an open fontanelle will be permanently open. I am a board member of our local humane society and I am adopting a one year old chihuahua with a very obvious open fontelle. He was nearly starved to death when he was recovered and also had a soft skull. he has since gained weight and energy and has become quite playful and charismatic. Will his skull continue to close up over the next year? If not, what can I do to ensure the longest happiest life for him?
    Reply to this
    1. 1/10/2009 5:04 PM Dr Kris Nelson wrote:

      Thank you for taking this dog in and providing a great home.  After all he has been through, it is wonderful for you to let him know love.  In most breeds of dogs, the fontanelles are closed at birth.  In Chihuahuas, it seems to take a little longer for closure to occur.  Up to nine weeks is considered normal.  At one year of age, I doubt the fontanelle will close.  I recommend performing an ultrasound through the soft spot to look for signs of hydrocephalus.  If the fontanelle is large (greater than 1/2 inch), I recommend getting a helmet for the little guy to prevent brain trauma.  Check with pediatric supply companies for helmets that can be modified to fit your dog.  If all else fails, you can used a 'doll' helmet although these are not crash proof by any means.  Again thank you for your kindness . . . you have warmed my heart.   

      Reply to this
  • 2/10/2010 4:03 PM Tammy wrote:
    I have a little pom that is 7 wks old and
    still has a small open fontenalle.
    He was the runt of the litter. None of the other sibs have it. He seems to be doing very well. He shows no signs of abnormality. He in fact eats very well and is very active. I wan to know how long I should wait to see if it will close. He does not show signs of hydrosephalis at this point.Can in develope later? Hr is 1 lb. 02 oz now.
    The hole is the size of a pea.
    Any info is appreciated.
    Reply to this
    1. 2/11/2010 8:26 PM Dr Kris Nelson wrote:
      Open fontanelles or soft spots are just as common in Pomeranians as Chihuahuas.  In my experience, I rarely see problems with ones that are less than 1 cm in size.  These dogs usually live a normal life without any clinical signs - unless they suffer a blow to the area. Since your puppy is only 7 weeks old, there is still a chance that the opening will close in the next two weeks.  If it does not, take him to your veterinarian for a neurologic examination.  They might be able to perform an ultrasound through the opening to look for signs of hydrocephalus.   

      Unfortunately, hydrocephalus may occur at any age.  I know of one dog with a large fontanelle who did well for two years before he started to seizure. 

      I wish you all the best with this little guy.  Pomeranians are one of my favorite toy breeds!    
      Reply to this
      1. 2/17/2010 1:24 PM Judie wrote:
        Would this apply to a French bulldog puppy? Our puppy is 7.5 weeks old with a 1 cm soft spot. The vet we took him to has not dealt with very many french bulldogs but thought it should be closed by now.
        Reply to this
        1. 2/18/2010 7:39 AM Dr Kris Nelson wrote:
          Yes, it applies to all the toy breeds.  An open fontanelle is not considered abnormal until 9 weeks of age. 
          Reply to this
  • 6/11/2010 1:55 PM Jessie from Texas wrote:
    I have a 5 yr F Chihuahua who has a rather large soft spot. She is just shy of 4 lbs and seems to have a lot abnormalities. Her tongue hangs out of the left side of her mouth 100 % of the time. It only goes that direction even when she drinks or gives kisses. When she is asleep, it comes out even further & also tends to dry up a lot. That is the first thing people notice about her. So along with her tongue, she also looks to be "pigeon toed", very clumsy, hypo-thermic and a pretty hard sleeper. But the thing that I fear the most is that she goes into seizure when she hits her head, even the slightest bit. Its only happened on a handful of occasions and I am extremely cautious about her surroundings;ie: things from above that have even a small chance of falling off and landing on her. This dog is my whole life and I try to do everything I can to keep her happy and healthy. I always knew she was on the cold side b/c she was constantly under blankets on laying on the heating pad when somebody in the house was using it for muscle aches would walk away. i got her her very own heating pad but quickly changed to a hot water bottle b/c i feared that she might get electrocuted. I also keep her in sweaters year-round b/c we keep the house pretty much the same temp no matter what season. When she was a puppy, I paper trained her b/c i was told that taking her outside could be dangerous exposing her to the germs and elements. So, she is inside 99.9% of the time. If I take her outside, its just for a few minutes. My family and I used to joke about getting her a helmet, but in the last year or 2, we have turned serious. She had a very bad accident a few months ago that involved a baby gate that was accidentally being kicked onto her. This was the worst incident that kept her in the vet's office all day then to the emergency clinic once my vet's office closed. They kept her on O2 therapy for hours to help the swelling of her brain. By the Grace of God, she survived, but I am very determined to get her a safety helmet. Since she will be wearing it 24/7 for the rest of her life, I want it to be custom made and fitted to where there is no danger of the strap choking her or anything like that. My husband and I have been looking on line for a while but we haven't found what we are looking for. I read your reply to another post where you suggested this person use a dolls helmet...Could you please suggest a place that would understand my dog';s needs and make the perfect safety device? I thank you in advance for any help you could offer. 
    Reply to this
    1. 6/13/2010 9:04 PM Dr Kris Nelson wrote:
      In my experience, the best place to find a pet helmet is at a serious bicycle shop in your area.  If that doesn't work, try or  The website has instructions for a do-it-yourself helmet.  I have not made one so I can't comment on the effectiveness of this.  You may also want to contact your local hospital's pediatric center or a pediatric neurologist and ask about protective helmets for infants.  Hope that helps!      
      Reply to this
  • 9/22/2011 4:12 AM wendy coates wrote:
    I have a 10 week old chihuahua who has an open fontanelle across his whole head, please let me know if there is anything I can do to help him have a good life as long as possible, I love him so much.....will he live a long life
    Reply to this
    1. 9/25/2011 7:43 PM Dr Kris Nelson wrote:
      Congratulations on the new puppy.  Unfortunately, it is difficult to predict how the open fontanelle will affect him.  I strongly recommend you get a consult from a veterinary neurologist to check for hydrocephalus.  If the lateral ventricles of his brain are within normal limits, he should have a good life as long as you protect his brain with a helmet.  Good luck with him! 
      Reply to this
  • 10/13/2011 11:01 PM Theresa Rentz wrote:
    Dear Dr. Nelson,
    I to have a 12 week old chihuahua puppy that has a very large soft spot. I am also in need of a protective helmet for my otherwise normal acting, sweet, lovable puppy. I am so glad I came across this blog site. Thank You for the useful info about helmets. I am going to try and make one for my little sweet girl and I hope I can come up with something that will help with her condition. I'm a former O.R. nurse and have worked with patients that needed this sort of protection and I hope that this exposure will help me design the protective headgear my little pup needs. I just love her so much!!! Again, thanks for being here for us and the other animal lovers out there that need the positive feedback you provide. God Bless You. Theresa
    Reply to this
    1. 10/14/2011 7:06 PM Dr Kris Nelson wrote:
      Thank you for the kind words.  I hope you puppy has a long, wonderful life. Thanks again, Dr. Nelson
      Reply to this
  • 10/15/2011 7:45 PM Michelle wrote:
    I have a 1 1/2 yr. male, 3.13 lb., Maltese that has a soft spot. About 3 weeks ago, i noticed him rapidly moving his rear right leg and holding his front paw stiff. He has continued to have these episodes, with no pattern. Does this sound like a seizure? No other problems.
    Reply to this
    1. 10/16/2011 11:22 AM Dr Kris Nelson wrote:
      Unfortunately, without seeing him have an episode, it is hard to say if this behavior is a seizure, spasm or reaction to an intense stimuli.  I would recommend videotaping him during one of these episodes.  It will greatly help your veterinarian get to the bottom of this health problem.  Keep a camera close by.  When and if he has another, note the duration, the environment and his behavior right beforehand.  The use of cameras and other video tools has been a wonderful diagnostic tool for clinicians.  It really helps us find answers for both medical and behavioral conditions.  I wish you the best of luck!  
      Reply to this
  • 8/20/2012 5:58 AM Tina H wrote:
    I Had 4 beautiful 5 week old chihuahua puppies,we recently introduced puppy food,and started soaking it in puppy milk for them,they all took to it fine,but we noticed 1 of the little girls hadnt pooed for at least 3days,so first thing this morning i took her to the vets,he said she has a congenital defect,was born with no bottom and was pooing from her vagina,and pooing into her womb,there wasnt anything he could do and said these things only come to light when you start to intoduce other than mothers milk, he advised me to put her to sleep,I holded her while the vet put her to sleep,im heart broken,but know she isnt suffering,ive brought her home and im burieing her in the our garden.wanted to post this so other chihuahua owners are aware of what to look out for in there puppies.still cant believe shes gone,so in peace Lola xxx
    Reply to this
  • 8/29/2012 5:34 PM Debbie wrote:
    Hi, I've read that poms are one of your favorite toy breeds, so I have a heart breaking story for you about my 5 month old, Millie.When Millie was 4 weeks old we learned she had a large fontanel and the vet that delivered her said she should wear a helmet. I said "really" thinking he was just joking. Four days after that visit Millie developed Nasal discharge and she had to be treated with antibiotics.At 6 weeks of age Millie's mom stopped producing Milk so I had to feed her formula through a syringe and I started her and her brother on canned food. Millie began eating it but began sneezing the food out of her nose and spitting it out. At 7 weeks the nasal discharge returned. She was eating very little and was lethargic. I took her to a 24 hr. emergency hospital (it was a sunday)in south Jersey. The vet that saw her noticed her fontanel which was not only on top but also on the sides.She told me Millie was blind and that was why she was not eating. Millie was not blind and was not eating because of the nasal congestion. She could not smell her food. She gave Millie fluids and sent her on her way with a death sentence. The following day I brought her to another vet in my area and she gave her a shot of penvk, pepcid (because she was vomiting mucous)and dextrose because her sugar was low.This was Jan. 30,2012. She had also lost 2 oz. We weighed them every week and she had been gaining 3 oz. per wk.On Feb 20th the congestion returned and given clavamox again.She was just to the vet on the 17th for a check and was well. On May 3rd she returned to vet for her second vaccine and on the following week the congestion returned. On the morning of the 17th(6:30 am), I gave her water through a syringe, this was the only way she would take fluids and her royal canin puppy food cut up small and nutrical.She was playing afterwards as normal and at 9 am I asked my daughter to give her water. When she picked her up (she had been sleeping)her eyes looked swollen and she was shaking so I took her to the vet thinking it was either a sinus infection or an allergic reaction to the nutrical. She gave her an injection of Diphenhydramine 2.5 mg and 10 mins later 0.25ml of Dex IM. Within 5 mins of the Dex Millie began excessively drooling. I took her home and she vomited a lrge amount of mucous and some food. I took her back to the vet at 2:30 and by this time she had begun bobbing her head when standing and when held she would be opisthotonus. She told me to take her to that same emergency hospital for a neuro consult. By the time we arrived Millie was in a semi coma.Her blood work showed low calcium and electrolytes. Millie had not had fluids or food all day because the pred. made her sick. Her crea was not even on the chart(low) and her Hb was low. Mon and Gran were high and WBC.
    She was put on fluids and clindamycin and was doing well by 9. the next day she had a neuro consult.See the rest on Youtube "in memory of our puppy millie"
    Reply to this
    1. 8/31/2012 8:20 AM Dr Kris Nelson wrote:
      Thanks for sharing!
      Reply to this
      1. 10/23/2012 7:06 AM Tina M wrote:
        Found the blog very useful as my daughter in law has a dog walking service and also fosters puppies in need. The latest foster "child" is a chihuahua cross with an open fontanella, the info in the blog has help ease our anxieties as this is out first experience of the breed. Thank you.
        Reply to this
        1. 10/23/2012 7:08 AM Dr Kris Nelson wrote:
          Thank you for your kind words.  And thank you to daughter for her work fostering dogs.  I hope the little one does well. 
          Reply to this
    2. 6/13/2013 5:43 PM Masako wrote:
      My Pom "runt" has open fontanels (now 13 weeks and 18 ozs) and was also vomiting and aspirating foamy mucus. She has also been having small seizures with excessive salivation. By feeding her more regularly (every 2-3 hours), she has quit with the vomiting. I notice that she has more seizures (daily) when over excited or right after her vaccinations. If I can keep her from getting too hyper with her litter mates, she's fine. I am also taking her out into the public more and if she gets scared or over stimulated, she then seems to have seizures. I am hesitant to take her to the vet because she is doing lots better. I have removed as much of the chemicals from her environment and food as possible. I have three kids in college and cannot afford to do all the tests and treatments. I am hoping that by giving her some extra care, she will still live a long and healthy life.
      Reply to this
      1. 6/14/2013 8:41 PM Dr Kris Nelson wrote:
        I'm afraid that even though Runt has a fontanel, that may not be the source of the problem.  I am worried she may have a liver shunt.  You need to see the veterinarian to have it diagnosed as there are medications and/or surgery that can help your puppy (assuming my diagnosis is correct).  I wish you the best of luck with both Runt and college.
        Reply to this
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