WHAT is Hydrocephalus in Dogs?

What is hydrocephalus in dogs? Chances are that you might never see a hydrocephalus dog in your lifetime unless you work in a veterinary hospital, a shelter, or any facility with dogs. 

You might wonder what hydrocephalus has to do with dogs and how often it happens? What are the risk factors? Should we concern ourselves about genetics and add it to our breeding checklist?

Right from middle and high school, we all had that one person in school or class we nicknamed “big head.” Probably, it was us that name was given to.  What we might not know is that we wrongly gave/accepted that nickname if the person (we) didn’t have hydrocephalus. This is because not all big heads are a result of hydrocephalus.

Hydrocephalus in animals may be rare to you, but it does occur. Let’s learn about one in the dog today. 

doctor holding brain

What is Hydrocephalus in Dogs? 

Hydrocephalus comes from the Greek word; hydro, meaning water, and Cephalus, meaning head. So literally, dog hydrocephalus means water in the head/on the brain of a dog. Medically, hydrocephalus is when excessive cerebrospinal fluid (CSF) escapes into the brain, thus, causing brain swelling. 

Cerebrospinal fluid is fluid around the brain and the spinal cord and housed in the skull and spinal vertebrae, respectively. It provides protection and nutrients to the brain and the spinal cord. Certain cavities in the brain procedures CSF, and the body absorbs it by other cavities to prevent buildup.

In the brain, the cavities drain CSF into the lymphatic system, where it mixes with the blood. These cavities are the subarachnoid space, foramen of Monro, aqueduct of Sylvius, foramina of Luschikae, and Magendie. Hydrocephalus occurs when a blockage occurs in these structures either congenitally or through an acquired method.

A dome head in a newborn puppy is normal and should close in a few weeks, around 9 – 12 weeks. The place where the dome shape fuses in an unaffected puppy is the rostral colliculi. Sometimes, this fusion creates a problem when there is not enough space left for the drainage of CSF. 

Hence, CSF leaks into the brain, a part called the white matter, because there is no space for drainage, which causes swelling and impedes the normal development of the brain.

Accumulation of CSF in the brain is due to certain factors such as:

  • Blockage in the drainage sites in the brain.
  • Too much production of cerebrospinal fluid in the brain 
  • There is a decreased absorption of the CSF in the brain. 

Since the skull prevents the brain from expanding, this increases the pressure in the brain (known as intracranial pressure), and the fluid presses on brain tissues that are sensitive, leading to brain damage, which can be irreversible. Most likely, death occurs. 

Symptoms of Hydrocephalus in Puppies

Symptoms of hydrocephalus vary depending on the cause and severity. However, there are general symptoms that run across dogs with hydrocephalus. Some dogs show no symptoms at all but might show signs of pain if not treated. 

Common symptoms in a hydrocephalus puppy/dog are:

  • A dome skull
  • Soft spot on the head (open fontanel)
  • Seizures
  • Blindness
  • Weak hind limbs
  • Slow growth
  • Runting (smaller than litter size)
  • Wide spaced/set eyes
  • Staring into space 
  • Change in behavior
  • Restlessness (lethargy)
  • Difficult housetraining
  • Circling, as a compulsive behavior
  • Difficulty eating and drinking
  • Uncoordinated movement or lack of coordination
  • throwing front limb about when walking
  • Bumping into walls and other things
  • Crossed limbs when standing
  • Inability to think or loss of memory (dementia)
  • Labored breathing
  • Coma
  • Unresponsive to stimuli
  • Head pressing 

These symptoms may not be entirely cut in stone and can differ. Once you notice anything different in your dog, kindly inform your veterinarian as soon as possible.

Since the presence of the fluid in the brain affects normal brain development and function, most of these symptoms are neurological. 

What Causes Big Foreheads in Puppies?

There are two main causes of hydrocephalus in puppies. These are those presented at/ gotten before birth (congenital) and acquired after birth. 

Congenital Hydrocephalus

Congenital hydrocephalus may be a result of a genetic condition, teratogens, or even an infection that crossed the placenta during brain development. In summary, it is a birth defect. It can also result from hemorrhages that clot in the brain after a prolonged labor or vitamin A deficiency gotten from the mother before birth. 

Additionally, congenital hydrocephalus can result from cysts in the nervous system, underdeveloped cerebellum, which affects fluid drainage, and abnormal skull size limiting brain growth and CSF function.

Congenital hydrocephalus leads to an enlarged fontanel (soft spot in the skull), a dome-shaped skull known as Waterhead or apple head, and eyes that seem to look/gaze downwards (known as the setting sun sign). 

Dogs affected congenitally do not show signs when they are very young or might show signs at birth. Congenital hydrocephalus diagnosis occurs during the weaning of the puppy (eating solid food and walking on its own).

Visible signs include: change in behavior, failure to obey basic commands or housetrain, falling over on one side, circling, and change in / abnormal walking.

Pet owners should note that not all dogs with big foreheads are hydrocephalus dogs, and it can be a result of other factors. 

Acquired Hydrocephalus

This occurs some years after birth and is usually due to infections, tumors, or trauma into the brain or any of its structures that maintains and drains the cerebrospinal fluid. A brain tumor is the most common form of acquired hydrocephalus. Other causes are parainfluenza virus, deficiency of vitamin A, intracranial inflammation, and brain hemorrhage that clots.

Signs of acquired hydrocephalus are similar to those of the congenital hydrocephalus and include; losing vision, circling, head pressing, seizure, pacing and restlessness, and behavior change.

Dog Breeds Susceptible to Hydrocephalus

Since hydrocephalus might have a genetic predisposition to it, there are certain breeds of dogs that are at risk / prone/ susceptible to getting hydrocephalus. Mostly, smaller dog breeds and those with snub noses or brachycephalic breeds are at a higher risk of developing hydrocephalus.

These dog breeds include:

  • Toy French Poodle
  • Boston Terrier
  • Yorkshire Terrier
  • Manchester Terrier
  • English Bulldog
  • Pekingese
  • Chihuahua
  • Cairn Terrier
  • Lhasa Apsos
  • Maltese
  • Pugs
  • Pomeranian 
  • Shih Tzu
  • Cavalier King Spaniel

Note that not all dogs from these breeds would develop hydrocephalus in their lives, and other dogs from less susceptible breeds may also be hydrocephalus.

Black Dog with big head

Is Hydrocephalus in Dogs Genetic?

Congenital hydrocephalus can have some genetic predisposition to it. Thus, you should not breed dogs with hydrocephalus or dogs that have produced a hydrocephalus dog. When buying, breeding, or adopting certain kinds of breeds or even dogs in general, look out for a family history of hydrocephalus before making a decision.

Acquired hydrocephalus, depending on the underlying cause, can be genetic also. For example, a dog’s generation with frequent brain tumors is most likely to be a genetic condition and, thus, shouldn’t be allowed to breed. Also, some dogs might have a gene mutation that affects their ability to absorb or convert vitamin A from their diet.   

In summary, it is not safe to breed hydrocephalic dogs, whether congenitally or acquired.

Is a Puppy With Hydrocephalus in Pain?

Is a puppy with hydrocephalus in pain? A hydro puppy will experience pain due to the pressure built up in the skull. This pain, depending on the severity and underlying cause, can range from moderate to severe. This pain might also result from the effect of the pressure on the eyes and the seizure occurrence. 

For acquired hydrocephalus, the pain might be a result of an infection or a tumor in the brain. The pain, depending on the location of the tumor, can affect other parts of the body, such as the neck.

Pain will prevent the dog from eating or performing normal activities. Your dog might withdraw and hide from you. It might be aggressive, shaking, or twitching. Remember that every dog responds differently to pain, and these signs might not necessarily be for all dogs.

A prescribed pain medication given to your dog can be at your request or if the veterinarian sees it necessary. 

Hydrocephalus in Dogs Life Expectancy 

Life expectancy for dogs with hydrocephalus varies depending on the age, type, and severity of the disease. Dogs with mild/moderate hydrocephalus can live a normal healthy life, usually occasionally on medication or rarely without any intervention. Dogs with severe hydrocephalus have a shortened lifespan, and death can occur at any time.

Dogs with congenital hydrocephalus do well after surgery in the absence of brain damage. However, dogs with acquired hydrocephalus do not readily do well due to the infection or tumor in the brain, which can cause encephalitis. 

Your dog might be on supportive treatment to keep it comfortable. You can discuss the prognosis with your veterinarian before you make any decision.  However, a dog with hydrocephalus will have a guarded prognosis, which means there is not enough information to tell the outcome, and there is a possibility it can result in a good or bad outcome.

How is Canine Hydrocephalus Diagnosed?

For young dogs and puppies, the clinical signs and the large fontanel is suggestive or diagnostic of canine hydrocephalus. However, it is prudent to run certain tests and imaging to rule out any other disease/ infection/ condition such as tumors. 

Your veterinarian would run a blood test for biochemistry analysis and complete blood count and urinalysis to rule out certain diseases that can manifest as hydrocephalus, such as viral infections.

The hospital would also use various imaging procedures (CT, MRI, X-rays) to diagnose canine hydrocephalus. 

Ultrasound is the first line of imaging tests employed in diagnosing. It will show the opening or the increase in the opened areas of the brain, known as brain ventricles. Equally, one can use a Computed tomography (CT) scan or a Magnetic Resonance Imaging (MRI) to diagnose congenital hydrocephalus.

For acquired hydrocephalus, the main diagnostic image of choice is the CT or the MRI. Sometimes, the veterinarian would connect electrical sensors in multiple locations on the head. Known as the Electroencephalography (EEG), it is very safe and poses no harm to your dog.

Also, the veterinarian can take an x-ray to see if there are any abnormalities or open spaces in the brain.

Treating Dogs With Dome-Shaped Heads

Treating can be successful in the early/ acute stages of hydrocephalus. Treatment often targets reducing the production of CSF in the brain and also reducing inflammation. Administering anti-inflammatory drugs such as prednisone, dexamethasone, prednisolone, or cortisone, collectively known as steroids or corticosteroids, is the first line of treatment.

For dogs that have had the hydrocephalus for a long time, such as in chronic cases or more severe cases, administration of acetazolamide, furosemide, omeprazole, or other proton-pump inhibitors and anti-seizure drugs like phenobarbitone is to manage the condition. Make sure to give them just as your veterinarian prescribes.

Ventriculoperitoneal shunt surgery is a surgery where a tube connects the brain ventricles to the abdomen and is performed under special circumstances by a neurosurgeon (brain surgeon) in specialized hospitals. This fluid in the abdomen reabsorbs into the body. 

The surgery has a high success rate when performed early on a hydrocephalus dog. Like all surgery, it has associated risks and complications. It is advisable to discuss it with the attending veterinarian and the specialist.

For acquired hydrocephalus, the main goal is to treat the cause of the hydrocephalus (underlying disease condition), and this would, in turn, correct the hydrocephalus. Treatment options include antimicrobials, chemotherapy, radiation therapy, and sometimes surgery. 

Always make sure to follow up on the treatment plan of your veterinarian, as well as any review or follow-up visits. If your veterinarian refers you to a specialist, be sure to go and follow all treatment plans at the specialist. 

white dog with big head


Dogs with hydrocephalus can live normal lives if detected early. However, do not breed them or their parents to prevent the condition from reoccurring. This condition does not spread from one dog to another. Hence a pet owner can rest assured of the safety of the rest of the kennel. 

Pet owners should ensure that vaccinations such as parainfluenza and parasite control are up to date. Also, add vitamin supplements to the dog’s food if it is deficient in it.  

Hydrocephalus in dogs doesn’t have to be a death sentence because there are various treatment plans available, and your dog can live a normal happy life with you.