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:
What is an open fontanelle?
Open fontanelles are soft spots in the skull, or gaps between the skull’s growth plates. They can be normal in young puppies, especially small breeds, but they typically close or harden by 9-12 weeks of age. In some breeds, such as Chihuahuas and Miniature Dachshunds, it is not uncommon for open fontanelles to persist beyond 12 weeks of age. In fact, open fontanelles in Chihuahuas are referred to as “moleras” and they are considered to be part of the breed standard, along with the classic dome-shaped skull.
Open fontanelles are a normal finding in very young puppies. As normal puppies mature, the growth plates in their skull fuse together and the soft spots known as open fontanelles gradually reduce in size until they no longer exist. Persistent open fontanelles, however, are a common genetic condition that is seen in some small dog breeds, including Chihuahuas, Miniature Dachshunds, Pomeranians, Shih Tzus, Yorkshire Terriers, Maltese, Lhasa Apsos, and Pekingese. In these dogs, persistent open fontanelles are caused by genetic abnormalities in normal developmental skull closure. The growth plates in these dogs simply fail to fuse in a normal manner, leaving a persistent soft spot in the skull.
In some cases, open fontanelles may be caused by an underlying brain condition, such as hydrocephalus. The term hydrocephalus means “water on the brain.” In hydrocephalus, cerebrospinal fluid (CSF) accumulates within the brain, causing the brain to swell. This swelling places pressure on the skull, which can contribute to open fontanelles, a dome-shaped skull, and other abnormalities. Fortunately, most cases of open fontanelles are genetic and are not associated with hydrocephalus.
How do you know if your fontanelle is closed?
The skull bones do not completely close during childhood because the brain still needs room to grow. However, once the bones grow to the point that they fill in the open spaces, the fontanelles are considered closed.