Hydrocephalus occurs when too much cerebrospinal fluid collects in and around the brain.

Diagnosis of the condition can be made based on ultrasound, CT or MRI.

Treatment may include medications or surgical placement of a drainage shunt.

Prognosis is dependent on the severity and cause of the disease.

What is hydrocephalus?

• The brain has four ventricles (fluid-filled spaces) within it. Cerebrospinal fluid (CSF) flows through these ventricles, bathes the central nervous system, and is eventually absorbed into the bloodstream via closed spaces (cisterns) at the base of the brain.
  
• Hydrocephalus occurs when too much CSF collects in and around the brain. Some causes of hydrocephalus are listed below. Hydrocephalus may be associated with an increased pressure on the brain and, in turn, this can cause damage to the brain.
  
• An animal can be born with hydrocephalus or it could develop later in life.
  
• Hydrocephalus is primarily seen in brachycephalic (short face) and toy breeds. Affected animals should not be bred.

Causes

• Obstructive - hydrocephalus could result from an obstruction that occurs somewhere in the ventricular system of the brain that prevents the CSF from flowing normally.
  
• Non-obstructive - hydrocephalus could result from increased production or decreased absorption of CSF.
  
• Encephalitis - inflammation of the brain.
  
• Meningitis - inflammation of the tissue surrounding the brain and spinal cord.
  
• Brain tumor.
  
• Head injury or bleeding in the brain.
  
• Infection of the central nervous system.

Clinical Signs

• Lethargy
  
• Seizures
  
• Developmental delay / slow learning
  
• Lack of coordination
  
• Eyes fixed downward
  
• Change in personality / irritability
  
• Domed skull
  
• Vomiting

Diagnostics

• The Veterinary Neurologist will evaluate physical, behavioral, and neurological abnormalities to make a preliminary diagnosis.
• A diagnosis of hydrocephalus can be confirmed with Computed Tomography (CT scan), Magnetic Resonance Imaging (MRI) or, in some cases, Ultrasonography.
• See the MRI (photo right) which demonstrates dilation of the ventricles of the brain (arrow points to the left ventricle)

Treatment

• The goal of treatment is to re-establish the balance of production and absorption of the CSF in the brain.
  
• Corticosteroids are used with a tapering dose to reduce the production of CSF in the brain. Usually this treatment has to be repeated.
  
• In some cases surgical placement of a shunt is required. This would divert the excess CSF to a different place in the body to be reabsorbed.

Prognosis

• In severe cases of congenital hydrocephalus, puppies often die early. 
  
• In less severe cases, signs may gradually become worse. Often, these puppies will stabilize with treatment.
  
• Sometimes, dogs with hydrocephalus may show no clinical signs at all.
• Affected animals are susceptible to other medical problems and may have a poor tolerance to various drugs.
  
• Even with treatment, some animals may have residual neurological damage.
  
• To minimize damage, start treatment early.