Water on the Brain in Dogs

Hydrocephalus, or water on the brain, is a condition in which fluid builds up within the cranium and puts abnormal pressure on the brain. This can lead to signs of neurological defects, though your dog may not exhibit any symptoms. The condition most commonly occurs in miniature, toy, and brachycephalic breed dogs, with young puppies developing the associated dome-shaped skull early on.

Dogs with hydrocephalus may exhibit neurological symptoms due to the increased pressure on their brains. Clinical signs include:

• Enlarged, dome-shaped skull
• Depression
• Seizures
• Uncoordinated movements
• Blindness
• Aggression
• Head pressing
• Regression in training

Typically, dogs that were born with hydrocephalus show the characteristic domed cranium at a young age, though other clinical signs may not be present or may progress slowly over time.

Types

Hydrocephalus may be congenital or may develop later in a dog’s life. Dogs with congenital hydrocephalus are typically smaller than average and are often the runt of the litter both in physical size and in mental development. Though they may not have any other obvious symptoms, many of these puppies do exhibit an enlarged head. Postnatal hydrocephalus occurs when the flow of cerebrospinal fluid (CSF) is blocked due to inflammation, a tumor, or trauma.

There are two types of hydrocephalus. Compensatory hydrocephalus arises when CSF production is increased to fill the empty space left by the loss of brain tissue. Obstructive hydrocephalus, which is the more common form found in dogs, is caused by restricted flow of CSF within the ventricles of the brain.

Hydrocephalus transpires when an abnormal amount of cerebrospinal fluid accumulates within the cranium, whether due to a congenital defect, a tumor, inflammation, or trauma. An obstruction may occur in an aqueduct and prevent CSF from draining properly, leading to a build-up in the cranium that places undue pressure on the brain. This is most commonly seen in miniature and toy breed dogs, with Chihuahuas being particularly predisposed to the congenital form of the condition. Brachycephalic dogs, such as the English bulldog, are also at a higher risk of developing hydrocephalus.

In puppies, an enlarged, dome-shaped head combined with signs of neurological defects are typically enough for the veterinarian to make a presumptive diagnosis of hydrocephalus. When you bring your dog into the veterinarian, you will need to provide a history, including the onset and extent of clinical signs that you have observed. The diagnosis may not need to be confirmed unless the symptoms progress.

Imaging provides a definitive diagnosis by revealing abnormalities in the cerebral ventricular system. An ultrasound can show dilated brain ventricles, though this is only possible in young dogs whose skulls have not yet fully fused. CT scans and MRIs are the general standards for diagnosing neurological conditions and can help determine the extent to which fluid has built up in your dog’s skull. Electroencephalography may also be useful for supporting the diagnosis.

Depending on the results of these scans, additional tests may be necessary to determine the cause of the hydrocephalus.

Treatment for hydrocephalus varies according to the extent of the fluid buildup in your dog’s cranium but is primarily geared towards removing excess cerebrospinal fluid from the cranium. Prior to making any decisions regarding your dog’s treatment, discuss your options with the veterinarian so that you understand the risks and the expected rate of success.

Medical Treatment

If your dog is exhibiting only mild signs associated with hydrocephalus, the veterinarian may recommend symptom management instead of treating the condition itself. Medication can relieve swelling and inflammation, as well as reduce the possibility of seizures. Certain drugs may also decrease the amount of CSF that is being produced, taking some of the pressure away from your dog’s brain.

Surgical Treatment

Surgery may be required in severe cases or if your dog’s symptoms progress. The veterinarian may refer you to a specialist, who will utilize a shunt to redirect CSF and establish a controlled flow of fluids away from the cranium, usually into the abdomen. There is a higher risk of complications with a shunt, though the overall success rate for surgical treatment is good.

If your dog received surgical treatment to address the hydrocephalus, you would need to monitor her closely for signs of infection or other developments. Make sure that your dog has a quiet place to recover in, and prevent him from biting at any incisions. Following both medical and surgical treatment, the veterinarian may wish to reexamine your dog to ensure that he is healing and that clinical signs are not progressing. Be sure to let the veterinarian know if you observe your dog exhibiting new symptoms consistent with hydrocephalus.

The prognosis for hydrocephalus is almost entirely dependent on the underlying cause for the condition and the extent of the fluid buildup and symptoms. The condition may be life-threatening, especially if left untreated for too long, but the prognosis is good in puppies that are treated quickly.