Hydrocephalus in Dogs- Classification, Causes, Diagnosis, Treatment

Hydrochephalus in Dogs
Hydrochephalus in Dogs

Hydrocephalus in dogs is a neurological condition. There is an accumulation of Cerebrospinal fluid on the brain inside the skull. This causes the head to appear enlarged and will almost always result in brain abnormalities. Here is more Classification, causes, diagnosis, and treatment of hydrocephalus in dogs.

Hydrocephalus in Dogs

Mostly phrased as “water in the brain” Canine Hydrocephalus is an abnormal increase in cerebrospinal fluid (CSF) in the dog’s brain within the ventricular system.

Hydrocephalus in dogs
Hydrocephalus in dogs

What happens is that there is an imbalance in the production, absorption, and flow of the cerebrospinal fluid in the dog’s brain. CSF accumulative build up in the dog’s brain causes an increase in pressure in the brain and later brings about health issues.

Classification and Type

Classification of canine hydrocephalus depends on how the imbalance occurs.  There are two ways of classifying Canine Hydrocephalus. It can either be Obstructive and Non-obstructive.


This is when the CSF is obstructed from flowing naturally within the ventricular system. It’s when CSF is obstructed from its natural flow within the ventricular system. This can be between or out of the ventricular regime of the brain. An imbalance in pressure occurs. Hence the reason it’s classified as non-communicative or obstructive.


The CSF flows out of the ventricular system into the spinal cord. It is however not reabsorbed by the surrounding tissue. However, this is rare and might sometimes correct its self, also known as communicating hydrocephalus.

Types of Hydrocephalus

There are two common types of canine hydrocephalus

Acquired hydrocephalus and congenital hydrocephalus. The types sometimes align up with the causes. This makes their knowledge very important to help with diagnosis and treatment.

Here are the types of canine hydrocephalus:

Acquires Hydrocephalus

This type of canine hydrocephalus develops after birth. It is a result of neurological health problems like infections e.g. meningitis, brain tumor, head trauma, intraventricular hemorrhage, or injury to the puppies or dogs brain.

Congenital Hydrocephalus

In this type, there is usually a problem during fetal development that led to the hydrocephalus. It may be due to teratogens, complex genetic interactions or physical problems such as trauma or infection when the mother is pregnant, and the fetus is developing.

Normal Pressure Hydrocephalus

This is when the ventricles of the dog’s brain become enlarged, but there is slight in pressure or no increase at all. Most often, the cause is not known. It occurs in older dogs normally from head trauma or infection.

Compensated Hydrocephalus

Diagnosed in older dogs.

What is the Cause of Canine Hydrocephalus?

Broadly categorized into congenital and acquired hydrocephalus.

Causes of Acquired Hydrocephalus

There are several causes of hydrocephalus in canines after birth. Here they are:

Brain tumor

The tumor in your pet grows obstructing or altering CSF flow.


Some diseases cause swelling or scarring on the dog’s brain membrane or spinal cord hindering CSF flow e.g. meningitis or parainfluenza virus

Head trauma

A knock or any other injury to the dog’s head may cause spinal cord damage, brain tissue damage, or damage to the nerves system leading to hydrocephalus because of blockage of the CSF flow in the brain

Intracranial inflammatory diseases

Exposure to any inflammatory causing disease, mostly at a young age, can lead to swelling of the dog’s brain hence leading to canine hydrocephalus.

Subarachnoid hemorrhage

Stroke due to burst blood vessel in the dog’s brain may result in blood flow in-between the brain and skull causing increased intracranial pressure.

Intraventricular hemorrhage

Mostly affects newborn puppies. The ventricular lining has small blood vessels alongside it that might burst which causes blockage of CSF absorption, resulting in building up of intracranial pressure.

Causes of Congenital hydrocephalus

It’s where genetics comes in. These cases happen during the dog’s pregnancy either infection, trauma on the fetus, etc. Here are the causes of congenital hydrocephalus in dogs:

Medication or drugs

There are some medications that interfere with the development of the fetus in the female dog. They are known as teratogens drugs e.g. Phenytoin (Dilantin), chemotherapeutic drugs, high dose steroids, or chloramphenicol


The mother might have suffered a prenatal infection while she was pregnant with the puppies. Some of the infections or diseases are Streptococcus, Brucella Canis, Aujeszky’s disease, canine herpesvirus, Toxoplasma, canine hepatitis, or Escherichia coli


The maternal dog (bitch) may have suffered a massive trauma experience that would have left the fetus development problems, leading to hydrocephalus. There may be bleeding in the brain caused by during birth.

Inherited hydrocephalus

An example genetic condition that leads to canine hydrocephalus include Dandy-Walker syndrome and Chiari malformation

Fetal tumor

There are some condition that some puppies are born with tumors in their brains, which they had while in their mother’s womb and may have brought about hydrocephalus

Dogs at Higher Risk of Having Hydrocephalus

Some dogs are more prone to congenital hydrocephalus (hydrocephalus present at birth). Acquired hydrocephalus isn’t specified to a particular breed of dogs because it can happen to any breed.

Miniature and toy breeds are more prone to the condition. They include:

  • Yorkshire Terriers
  • Chihuahuas
  • Bulldogs Breed Predilections
  • Cairn Terriers
  • Pugs
  • Pekingese
  • Boston Terriers
  • Maltese
  • Toy Poodle
  • Pomeranians
  • Manchester Terrier
  • Lhasa Apsos

Symptoms of Hydrocephalus in Dogs

Some puppies with hydrocephalus don’t have clinical symptoms. They will only develop these signs when something disruptive happens i.e. trauma or infection.  Canine hydrocephalus symptoms depend on Age of dog, Amount of brain damage caused by hydrocephalus, what’s the reason for the buildup of CSF fluid and the area of harm.

After birth, the puppy’s skull is not fused completely. The symptoms are not easily noticeable until the puppy is about eight to twelve weeks old. The symptoms include:

  • There are behavioral signs – lack of or loss of training ability
  • Excessive Sleepiness or Drowsiness
  • Eyes with the appearance of gazing downwards “Ventrolateral strabismus.”
  • Seizures
  • Vomiting
  • Visual impairment which later leads to blindness
  • Gait abnormalities
  • Lack of coordination “ataxia.”
  • Stunted growth
  • Circling (falling over on one side)
  • Dome-shaped or apple shape puppy skull and soft spot on the top of the head
  • Separated sutures
  • Abnormal breathing patterns in severe cases may result in death
  • Coma
  • Hyperexcitability
  • Head tilt
  • Altered mental state “dullness or slow in thinking.”

Clinical signs cannot sufficiently prove the presence of hydrocephalus condition you need a vet opinion on the matter. Provide the dog’s history and his parents’ history, if available, for the Veterinary neurologists to come up with a conclusive diagnosis.


Early detection and proper diagnosis are very essential. It helps in minimizing the chances of complications in terms of severity and even long-term health issues for your dog.

A qualified vet should do the exams and tests. The vet will first need a medical history of the dog and later perform a physical examination which will help him/her have a better idea of what to check for when he uses more advanced types of equipment for diagnosis.

The vet will first do a physical examination to show:

  • Presence of deformity of the skull
  • If the dog’s frontal head is larger than normal
  • Eyes seem unusual and are sunken in
  • Swollen veins on the puppies head

Other physical exams

  • Chemical blood profile
  • Complete blood profile
  • Urinalysis
  • Complete blood count

All these tests and exams help confirm or rule out evidence of cancer, infection, disease or trauma. For a more definitive diagnosis, the vet neurologist will have to perform neurological examinations and tests on the puppies.

Advanced Diagnostic Methods:

CT scan (Computerized Tomography)

This is one of the best tests used by Veterinary neurologists in identifying canine hydrocephalus. CT is a standard imaging method used by vets in diagnosing neurological defects. The scan will be able to tell the size of the ventricles. It will also show whether there is an enlargement of the ventricles or brain atrophy. CT scans may be able to pick out the lesion that causes obstruction.

The imaging of the scan display can give a lot of information about the situation inside the dog’s head and determine the exact source of CSF build up.

MRI (Magnetic Resonance Imaging)

MRI also favorite for vets, who perform neurological tests; it has quality imaging with increased spatial resolution and tissue contrast. MRI easily identifies tumors, cysts, and granulomas. This is one of the reasons why MRI is regarded as accurate in diagnosis. It also reveals the primary cause.

Head and Skull X-Ray

A radiograph of the dog’s skull and head may help reflect the anatomical changes which come about as a result of hydrocephalus.

Brain Ultrasound

The cerebral ventricular system is easily identified by an ultrasound showing the range of the dilated lateral ventricles and checking its changes over time.

Other tests which can be done:

  • Examination of the cerebrospinal fluid

Vets rarely do it depends on the severity of the case. The lumbar puncture procedure is used.

  • Also, an electroencephalogram (EEG) can be used to measure the brain’s electrical activity and help support diagnosis of the hydrocephalus.
  • Arteriography
  • Fecal analysis


The goal of treatment is to reduce production of CSF and increase its flow or remove the primary cause that’s bringing CSF flow obstruction or alteration. The type of therapy depends on the severity of the condition and might sometimes need prolonged treatment from time to time or hospitalization of the sick dog.


Although medication is available, it only used in mild cases. It’s recommended in managing acute deterioration. Drugs are also used to reduce risks of seizures, relieve inflammation and others are used to reduce CSF production “Diuretics, acetazolamide or glucocorticoids” hence relieving the brain of pressure. However, medication is just a temporary solution to the problem.


When medication fails in controlling hydrocephalus or hydrocephalus is found to be its severe case then surgery is needed for definitive treatment. The aim of the operation is to establish control of cerebrospinal fluid (CSF) flow.

After the primary cause of hydrocephalus has been discovered there is the surgical treatment which may involve direct removal of the obstruction, or a ventriculoperitoneal shunt placement surgery.

The CSF is shunted from the ventricles of bog brain through a subcutaneous tunnel to the abdominal cavity and a distal shunt towards the valve.

All this is why the procedure is very expensive.

Clinical signs may not be resolved completely and also underlying cause may not have been resolved. The vet neurologist will start focusing on them. There may be radiation therapy for dogs with a tumor or even tumor removal, and there will also be medication.

Side effects

Both the surgery and medication have side effects they include:

  • Cerebral infection.
  • Tube separation
  • Nerve damage or physical disability
  • Electrolyte abnormalities from the medicines

Preventing Hydrocephalus in Dogs

  • Don’t breed dogs with hydrocephalus with other dogs,
  • Protect the small puppies from a head injury
  • Ensure you watch over and assist your dog while it’s giving birth
  • Prompt treatment of any infection or disease to pregnant mother and puppies to prevent or reduce the risk of hydrocephalus.

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