Hydrocephalus in Dogs

Causes, Treatment, and Prevention

Chihuahua puppy with hydrocephalus
Hydrocephalus causes the head to swell.

Getty Images/cynoclub

Hydrocephalus in dogs is a disease that affects the brain. The disease is more common in small and brachycephalic breeds but it can occur in any dog. The severity of the problem will vary from dog to dog but it is a life-threatening condition that needs aggressive veterinary attention.

What Is Hydrocephalus?

Hydrocephalus occurs when cerebrospinal fluid (CSF) builds up in and around a dog's brain. It is often referred to as "water on the brain" since that is what the word hydrocephalus means. Normally, CSF flows around the brain and into the spinal cord and gets absorbed by the body. But in dogs with hydrocephalus, either too much of this fluid is being produced or it is not able to be properly absorbed into the body. Because there is too much fluid and not enough space to store it, it leaks into the skull which puts pressure on the brain.

Symptoms of Hydrocephalus in Dogs

The pressure in the brain results in the various symptoms pet owners may see in dogs with hydrocephalus. In dogs, hydrocephalus is classified as either congenital (primary) or acquired (secondary) and requires urgent veterinary attention.


  • Swollen head
  • Fontanel
  • Seizures
  • Behavioral changes
  • Slow to learn
  • Eye issues

Swollen Head

Since dogs with hydrocephalus are experiencing excess CSF in their head, it is not abnormal for them to have head swelling. The forehead or the entire skull may appear larger than usual due to the fluid pushing on it, especially if the dog is a young puppy.

A bubble or dome shape is often used to describe the head of a dog with hydrocephalus. Young puppies with hydrocephalus may have softer skulls that can expand to accommodate the fluid but, once the skull hardens, the brain is put under pressure. This pressure then causes the other symptoms of the disease.


A puppy with congenital hydrocephalus may have a large fontanel (also called an open fontanel), or soft spot at the top of its head that can indicate a gap between the skull's growth plates.

Fontanels, however, may be normal in younger small breed puppies. By 12 weeks of age, the fontanel should harden, though the softness may last a bit longer than that in some dogs. If the soft spot persists much beyond 12 weeks, however, it may indicate hydrocephalus.


Due to the increased pressure on the brain, seizures may occasionally be seen in dogs with hydrocephalus but they are not as common as once thought.

Behavioral Changes

Abnormal behaviors like lethargy, head pressing, loss of coordination, and irregular walking patterns, are often seen.

Slow to Learn

Puppies with hydrocephalus may also be especially slow at learning things. For example, a puppy with the disease will be unable to learn to be housebroken.

Eye Issues

Blindness, abnormal eye positioning, and other ocular issues are sometimes present in dogs with hydrocephalus. Congenital hydrocephalus will present with lateral deviation (both eyes pointing in the same direction) of the eyes in puppies, for example.

Causes of Hydrocephalus

Hydrocephalus is caused by an obstruction or decreased absorption of normal CSF flow. In dogs with congenital hydrocephalus, the problem is something the puppy is born with and symptoms begin to show within weeks of birth. What exactly causes this abnormality in puppies while they are developing is not always known. In dogs with acquired hydrocephalus, the obstruction or decreased absorption of CSF is the result of another brain disease like a brain tumor.

While any breed of dog is capable of developing hydrocephalus, certain breeds are more prone to the disease. Certain dogs are especially at risk to develop hydrocephalus including these toy and brachycephalic breeds:

Diagnosing Hydrocephalus in Dogs

If you suspect your dog has hydrocephalus, a full physical examination by a veterinarian should be performed. Physical and neurological symptoms may lead your vet to recommend diagnostic testing.

If your dog has an abnormal opening in its skull called a fontanelle, an ultrasound may be performed, otherwise, a CT or MRI is typically recommended. Other tests including an EEG and an analysis of the CSF may also be obtained.


Treatment of hydrocephalus will vary depending on how severe the disease is. There are two possible treatment paths:

  • Medicine: Neurological symptoms, like seizures, will need to be managed but the amount of CSF also needs to be addressed. An anti-seizure drug called omeprazole is commonly used to decrease CSF but steroids such as cortisone and prednisone may also be used. 
  • Surgery: Surgery to place a shunt and tube to help drain the extra CSF from the brain into another acceptable location, such as an abdominal cavity, may also be necessary if medications alone do not provide long-term relief. This surgery is not commonly done since it is costly and not many veterinarians perform it.

Prognosis for Dogs With Hydrocephalus

If treatment options do not help a dog with hydrocephalus or if surgery is not an option, euthanasia is often elected once the disease can no longer be managed. If a dog does have the shunt surgery, complications with the shunt connection, any obstruction, or subsequent infections may occur after three months.

How to Prevent Hydrocephalus

Hydrocephalus is not a contagious disease so it is difficult to prevent it. The best thing you can do to prevent a dog from developing this disease or being born with it is to practice selective breeding and purchase puppies from reputable breeders. Dogs with hydrocephalus or those that have a familial history of hydrocephalus should never be used for breeding purposes.

Article Sources
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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