What Is Hydrocephalus in Dogs?

If your vet just mentioned “water on the brain,” it’s okay to feel rattled. Hydrocephalus means cerebrospinal fluid (CSF), the fluid that normally cushions and protects the brain, is building up inside the skull and putting pressure on the brain tissue. That pressure is what causes the symptoms you might be seeing. It shows up most often in toy breeds and small dogs, sometimes from birth and sometimes later in life. While it sounds scary, many affected dogs live comfortable, good-quality lives with the right care.

Congenital vs. acquired hydrocephalus: what’s the difference?

There are two ways a dog can develop hydrocephalus, and the distinction matters for treatment and outlook.

Congenital hydrocephalus means a puppy is born with it. The CSF drainage system didn’t develop properly in the womb, so fluid builds up from the start. This is the more common form in toy and brachycephalic (flat-faced) breeds. You might notice signs in the first weeks or months of life.

Acquired hydrocephalus develops later, usually because something disrupts normal CSF flow. That could be a brain tumor pressing on a drainage pathway, inflammation from an infection, a head injury, or brain swelling from another cause. Any dog, at any age, can develop the acquired form.

What are the signs of hydrocephalus in dogs?

Some signs are visible before you even get to the vet. Others are behavioral and easy to mistake for something else.

Physical signs

• Dome-shaped or apple head skull: the head looks abnormally rounded or enlarged, especially around the top
• Open fontanelle (soft spot): a gap in the skull bones that never closed, similar to the soft spot in human newborns
• Setting sun sign: the eyes appear to gaze downward, with the whites showing at the top, because of pressure on the brain

Behavioral and neurological signs

• Seizures
• Circling or walking in one direction compulsively
• Difficulty with house training, even in older dogs
• Appearing confused, disoriented, or slow to respond
• Vision problems or apparent blindness
• Trouble coordinating movement
• Restlessness or crying, especially in puppies

Not every dog will show all of these. Some cases are mild enough that the main sign is just a soft spot and a slightly domed head, with minimal neurological impact.

Which dogs are most at risk?

Hydrocephalus is far more common in toy breeds and small dogs than in larger breeds. Chihuahuas, Boston Terriers, Maltese, Pomeranians, Yorkshire Terriers, Pugs, English Bulldogs, and Lhasa Apsos are among the breeds most frequently affected. If your dog is one of these breeds and you’re noticing any of the signs above, especially a dome-shaped skull or an open soft spot on the head in a young puppy, it’s worth calling your vet sooner rather than later.

Diagnosis: what to expect at the vet

Your vet will start with a full physical and neurological exam, checking things like reflexes, gait, and eye movement. But confirming hydrocephalus requires imaging.

• MRI (magnetic resonance imaging): the gold standard for diagnosing hydrocephalus. It gives detailed pictures of the brain and shows exactly where CSF is accumulating and how much pressure is involved.
• CT scan: faster and more widely available than an MRI. It can identify enlarged fluid-filled spaces in the brain and rule out a brain tumor as the underlying cause.
• Ultrasound through the fontanelle: in puppies with an open soft spot, a vet can sometimes use ultrasound to get a preliminary look at the brain’s fluid spaces before moving to an MRI or CT scan.

These diagnostics aren’t cheap. MRIs and CT scans for dogs typically require general anesthesia and a specialist facility, so it’s worth knowing that going in.

What are the treatment options for canine hydrocephalus?

Treatment depends on how severe the condition is and whether it’s congenital or acquired.

For mild to moderate cases, medication is usually the first approach. Corticosteroids like prednisone help reduce brain swelling and ease pressure, while omeprazole, the same drug used for acid reflux in humans, has been found to reduce CSF production in dogs and is often used alongside other medications. Diuretics may also be added depending on the case.

For more severe cases, a VP shunt is the most effective long-term option. This is a surgical procedure where a small tube is placed in the brain to drain excess CSF into the abdomen, where the body reabsorbs it. Many dogs show significant improvement after the procedure, but it’s a meaningful surgery with real risks and a real recovery period. It’s a decision to make carefully, ideally with a veterinary neurologist guiding the conversation.

Living with a hydrocephalic dog: day-to-day care and what to watch for

Managing hydrocephalus isn’t just about the diagnosis and the treatment plan. It’s about what daily life actually looks like, and how to keep your dog comfortable and safe at home.

Daily management

What to do	Why it helps
Keep the environment calm and consistent	Dogs with elevated brain pressure can be sensitive to noise, excitement, and temperature changes. Routine reduces stress and the risk of flares.
Avoid rough play and extended exercise	Anything that involves a lot of jumping, head-down postures, or aerobic exertion can temporarily spike pressure. Short, gentle walks are the better option.
Elevate food and water bowls slightly	Eating and drinking with the head lowered for long periods can increase intracranial pressure. A small raised stand makes a real difference.
Stick to the medication schedule	Whether your dog is on prednisone, omeprazole, or both, consistency is critical. Missing doses can trigger a flare.
Pad sharp corners and low edges	Dogs with neurological symptoms may lose balance or bump into things. Foam corner guards and low-pile rugs can prevent injuries.

Warning signs of a pressure flare

Know what a bad day looks like so you can act quickly. Call your vet or head to an emergency clinic immediately if you notice any of the following:

• A sudden increase in seizure frequency, or a seizure lasting more than a couple of minutes
• Rapid loss of coordination or a sudden inability to walk
• Extreme lethargy, unresponsiveness, or collapse
• Sudden blindness or a dramatic change in eye movement
• Crying or whining that seems pain-related and won’t stop

These are emergency situations, not wait-and-see moments.

Life expectancy and survival rate: honest answers

If this is the question keeping you up at night, that makes complete sense. It depends on the severity, and the range is wide. Dogs with mild cases managed well with medication can live relatively normal lives for years. Dogs who undergo successful VP shunt surgery often show dramatic improvement and go on to have a good quality of life long-term. For dogs with severe or rapidly progressing hydrocephalus, particularly when linked to an underlying cause like a brain tumor, the outlook is more guarded.

Early diagnosis and consistent treatment are the biggest factors in a better outcome. It’s not a death sentence, but it is a condition that asks a lot of both the dog and the owner. Take it one step at a time, lean on your vet, and know that many families have navigated this and found their footing.

Does pet insurance cover hydrocephalus in dogs?

Yes, hydrocephalus is eligible for coverage under a Lemonade Pet accident and illness policy, as long as the condition isn’t pre-existing. That means your dog shouldn’t be showing any signs or symptoms before your policy starts or during your waiting period.

The costs can add up fast. An MRI or CT scan alone can run into the thousands, and that’s before medications, specialist visits, and potentially VP shunt surgery. Getting coverage in place while your dog is healthy is what makes it actually useful when you need it most.

Before we go

A hydrocephalus diagnosis is a lot to absorb, especially when it’s your dog and you just want to know they’re going to be okay. The honest truth is that many dogs with this condition do live happy and comfortable lives, especially with and early diagnosis, the right treatment plan, and an owner who knows what to watch for. You’re already doing the right thing by educating yourself. Talk to your vet about imaging and ask about a referral to a veterinary neurologist.

If your dog is and at-risk breed, and still young and healthy, look into getting a Lemonade Pet policy in place now, before symptoms arrive.

Frequently Asked Questions

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.