Hydrocephalus in Dogs: Symptoms, Causes, Diagnosis


Hydrocephalus in dogs is a serious and often life-threatening disease that develops when fluid on the dog’s brain piles up and causes several points of pressure on the brain. Treatment may be medication, therapy or surgery and is typically determined by the cause, type and severity.

What is Hydrocephalus in Dogs?

Hydrocephalus in dogs is a rare neurological disease that happens when there is pressure on the dog’s brain caused by an excessive amount of cerebro-spinal fluid (CSF). A common name for hydrocephalus is “water on the brain” although this is not what the fluid is at all, but rather CSF that coats areas of the brain as well as the spinal cord. In a dog with hydrocephalus, the fluid, for whatever reason, does not drain properly, and this causes severe dog’s brain pressure.

Hydrocephalus can affect adult dogs because of complications stemming from several different diseases, or a puppy can be born with the hydrocephalus. Although hydrocephalus affects various species of animals, it is most common in dogs despite it being a rare disease.

Hydrocephalus in dogs is categorized as one of two types.

Acquired Hydrocephalus

Typically affects older dogs, is the type that happens when tumors, infections or inflammation grow and prevent the drainage of the fluid. This type may also be caused by obstructive or secondary hydrocephalus. Brain tumors are responsible for most cases of hydrocephalus in adult dogs.

Congenital hydrocephalus

This is the type that puppies are born with. It’s often caused by an issue during fetal growth.


Smaller breed dogs are more prone to have congenital hydrocephalus, especially breeds with a dome-shaped head or a short face (brachycephalic). The breeds most commonly affected include:

  • Boston terriers
  • Chihuahuas
  • Yorkshire terriers
  • Toy poodles
  • Maltese
  • Pekingese

It’s believed that the reason it’s so common with miniature or small breed dogs is that when breeding the dogs alters the skeleton quicker than the soft interior tissues, which results with the brain insufficient size for the skull, which in turn blocks the pouring of CSF. Because hydrocephalus in canines is congenital or genetic in mature, breeders and owners are advised to not breed any of the dogs in the litter that are affected with hydrocephalus.

Secondary or acquired hydrocephalus can develop for a few different reasons.

  • Fungal infestations
  • Parainfluenza virus
  • Parasitic infestation
  • Immune dysfunctions


Although congenital hydrocephalus affects puppies when they’re born, they are usually not diagnosed until they’re at least six months old. They may be symptomatic at birth, but they’re not always recognized until they worsen and become more prominent over time. This is probably another reason why congenital hydrocephalus is not as serious as with adult dogs.

One of the main symptoms seen in puppies with congenital hydrocephalus is head pressing, pacing and eyes that look outwards or look down almost all the time. Common symptoms of congenital hydrocephalus in canines include:

  • Head with a dome appearance
  • Blindness or decreased vision
  • Difficulty in learning basic commands
  • Large, open or soft spot in the skull
  • Regular circling
  • Seizures
  • Inability to house break
  • High-step or spastic walking
  • Restlessness and pacing
  • Pressing head against the wall
  • Coma

Symptoms are usually more severe in adult dogs than with puppies.


Diagnosing hydrocephalus is not always easy because it is such a rare disease. However, if a puppy is of a certain age, is a smaller breed and has some of the symptoms of congenital hydrocephalus, particularly the dome-shaped head, a veterinarian may suspect the disease. If the dog is an adult, diagnosis may be more difficult because the symptoms are so similar to many other diseases.

One of the first diagnostic tools used is a blood test to rule out any other diseases that may have similar symptoms. Blood tests are also effective in diagnosing viral infections. If a puppy is brought in with the soft spot on its head, the vet may perform an ultrasound of the brain. The vet will do an ultrasound on top of the soft spot, which allows him or her to view the brain.

Ultrasound is ineffective with adult dogs or puppies with a closed fontanel. In these cases, the vet will use a brain scan, typically a CT scan or an MRI, while the dog is given anesthesia. If a vet doesn’t have these high-tech machines, the dog owner may need to find a larger veterinary hospital with a neurologist.

Another method of diagnosis is obtaining a sample of the dog’s CSF. This is done by inserting a needle in the dog’s spinal cord. Occasionally, the vet may use an electroencephalography (EEG) to check the dog’s brain activity.


When the dog is first diagnosed with hydrocephalus, the treatment is focused on stopping the production of CSF and reducing clinical symptoms like seizures. The majority of dogs with hydrocephalus can be managed with medication, but the disease will never be completely cured. The first medications typically used for congenital hydrocephalus are steroids like cortisone or prednisone.

These medications can reduce not only the production of CSF and inflammation. Dogs suffering with seizures may also receive anti-epilepsy drugs. In all cases of hydrocephalus, the earlier the dog receives treatment, the better the chance of some sort of recovery.

If possible, the vet may do a surgical procedure where they put a shunt or drain in the brain to get rid of the fluid. The negative part of this is that only a surgical specialist can perform this procedure. Puppies who have this procedure done at a young age often have the best chance. Radiation therapy may also be used for brain tumors. Medications used to treat hydrocephalus include:

  • Prednisone
  • Furosemide
  • Omeprazole
  • Levetiracetam
  • Mannitol

Regardless of what type of treatment the dog requires, treatment for this disease is expensive.


Unfortunately, there is really no way to prevent hydrocephalus. Since congenital hydrocephalus is often genetic, any affected puppies and parents should never be used for breeding purposes because the risk is very high of getting more puppies with hydrocephalus.

Even if only one puppy in the litter has the disease, none of the litter should be used for breeding. In the case of adult dogs, while there is no prevention, providing the dog with regular vaccinations for parainfluenza and parasites can play a big part in prevention.