Tiny dogs with dome-shaped heads are at risk for a brain problem called hydrocephalus. Knowing how to recognize hydrocephalus will help you get your dog treated before serious brain damage occurs.
hand comforting a small dog with hydrocephalus
Credit: Anna Krivitskaya / Shutterstock

Who doesn't love the cute face of a Chihuahua, with their dome-shaped heads and wide-set eyes? Well, those adorable faces put Chihuahuas and other little dogs at risk of a brain condition called hydrocephalus, also known as "water on the brain."

Hydrocephalus in dogs, although uncommon, is serious and requires prompt veterinary care to avoid permanent and possibly life-threatening brain damage.

Hydrocephalus certainly sounds scary, but knowing what it looks like and how it can be treated will help you get your dog the treatment they need if they have this condition.

What is Hydrocephalus?

Hydrocephalus is the buildup of cerebrospinal fluid (CSF) in the brain. CSF surrounds the brain and spinal cord, providing nutrients and cushioning these delicate tissues that make up the central nervous system.

CSF can build up if too much is being produced or the body is not properly absorbing it. This buildup increases pressure on the brain and can cause severe brain damage if not detected and treated early.

Causes of Hydrocephalus in Dogs

Hydrocephalus is categorized as either congenital or acquired, with different causes for each. Congenital hydrocephalus is more common than acquired hydrocephalus.

Congenital Hydrocephalus

Congenital hydrocephalus is present at birth. It is typically due to abnormal development of the fetus during pregnancy that causes affected puppies to have soft, dome-shaped skulls. As the puppies age, their skulls harden and the outflow of CSF is blocked.

Small breed dogs and brachycephalic ('smoosh-faced') dogs are most susceptible to congenital hydrocephalus, including breeds like these:

Acquired Hydrocephalus

Acquired hydrocephalus is caused by something that occurs later in a dog's life, most commonly a brain tumor. Other causes are listed below:

  • Brain trauma
  • Brain hemorrhage
  • Brain infection
  • Inflammatory brain disease

Signs and Symptoms of Hydrocephalus in Dogs

The symptoms of congenital and acquired hydrocephalus are similar but occur at different time points in a dog's life: less than six months of age for congenital hydrocephalus and during adulthood for acquired hydrocephalus.

Puppies with congenital hydrocephalus may look normal at birth other than a dome-shaped skull, wide-set eyes, and possibly an open fontanel (soft spot on top of the head). However, as the CSF builds up in the brain, other symptoms become apparent. Here's what you may notice:

  • Seizures
  • Stupor
  • Coma
  • Vision loss
  • Lethargy
  • Spastic walking
  • Head pressing
  • Walking in circles
  • Slow pace of learning
  • Not very responsive to stimuli
  • Inappropriate vocalization
  • Hyperexcitability

These symptoms tend to be severe in older dogs with acquired hydrocephalus.

Schedule an appointment with your veterinarian as soon as you can if you notice these signs in your dog.

How to Diagnose Hydrocephalus in Dogs

Hydrocephalus requires a veterinary diagnosis.

The presence of a dome-shaped head and open fontanel, along with other hydrocephalus-related clinical signs, is often enough to diagnose congenital hydrocephalus. Diagnosing acquired hydrocephalus is not as straightforward, particularly because other diseases can cause similar symptoms.

After examining your dog, your veterinarian will want to perform imaging tests of your dog's brain, including ultrasound. Ultrasound is a good option for puppies with an open fontanel because the open fontanel would allow your veterinarian to see your dog's brain.

Advanced diagnostic imaging options are computed tomography (CT) and magnetic resonance imaging (MRI), which veterinary radiologists perform. CT and MRI are recommended for dogs without an open fontanel but are suspected of having hydrocephalus. Dogs need to be anesthetized for these tests.

CSF analysis can help determine the underlying cause of acquired hydrocephalus. For example, inflammatory cells in the CSF can point toward an infection.

How to Treat Hydrocephalus in Dogs

Hydrocephalus must be treated early to have the best chance of success. The main treatment goals are to stop CSF buildup in the brain and reduce symptoms.

Your veterinarian will determine the best treatment option for your dog according to your dog's age, neurologic status, and severity of symptoms.

For mild to moderate hydrocephalus (usually congenital hydrocephalus), treatment will begin with medications:

  • Steroids to reduce inflammation and brain swelling
  • Diuretics to increase the outflow of CSF and decrease CSF production
  • Omeprazole to reduce CSF production
  • Anti-seizure medications

Surgical placement of a shunt is recommended if the hydrocephalus is severe (usually acquired hydrocephalus) or isn't responding adequately to medications.

This shunt has a complicated name—ventriculoperitoneal shunt—and redirects the flow of CSF into the abdomen. It is a long-term treatment solution and has a success rate between 50 and 90 percent.

As they grow, puppies with congenital hydrocephalus will need subsequent surgeries to replace the shunt with a larger shunt.

Shunt placement is complex and not without risk. Many veterinarians are not comfortable performing this surgery. Surgical complications include shunt blockage and infection within the shunt.

Life Expectancy for Hydrocephalus in Dogs

The life expectancy for dogs with hydrocephalus depends on several factors, including the dog's age and how severe and longstanding the hydrocephalus is.

Puppies with congenital hydrocephalus can do well if they have shunt surgery before severe brain damage has occurred. Older dogs with acquired hydrocephalus have a more guarded prognosis because of the severity of the underlying condition (e.g., brain tumor). Your veterinarian will discuss your dog's likelihood of recovery with treatment.

Shunt surgery is expensive, in part because it is performed by a veterinary surgeon who specializes in neurologic surgery. Be prepared to spend several thousand dollars for the surgery. Pet insurance can help defray the cost of treatment, but the insurance policy may need to be in effect before your veterinarian diagnoses the hydrocephalus.

Hydrocephalus in dogs is a serious and life-threatening condition. If your dog has any signs of hydrocephalus, take them to your veterinarian for prompt diagnosis and treatment.