Cerebrospinal fluid

Function of the CSF

The CSF has several important functions for your dog's nervous system. It:

• cushions the brain and spinal cord from impacts and injuries
• Regulates the pressure in the skull and spinal canal
• Protects against infections and inflammation
• Supplies oxygen, glucose and other nutrients to the nerve cells
• Removes waste products and toxins from the nervous system

CSF is constantly produced in special cells, the choroid plexus, which are located in the ventricles (cavities) of the brain. From there, it circulates through the brain, the spinal canal and the subarachnoid space (the space between the meninges). The CSF is then reabsorbed into the veins located on the surface of the brain.

Examination of the CSF

CSF testing can provide important information about the health of your dog's nervous system. A small amount of CSF is taken from the spinal canal or skull, usually under anesthesia or sedation. This procedure is known as a lumbar puncture or cisternal puncture. The extracted CSF is then analyzed in the laboratory for various parameters, such as

• Color and clarity: the CSF should be clear and colorless. Clouding or discoloration may indicate infection, bleeding or inflammation.
• Cell count and differentiation : The CSF should contain only a few cells, mainly lymphocytes (a type of white blood cell). An increased cell count or a change in cell types may indicate infection, inflammation, tumor disease or autoimmune disease.
• Protein: The CSF should have a low protein content. An increased protein content may indicate a disturbed blood-brain barrier, inflammation, infection or tumor disease.
• Glucose: The CSF should have a similar glucose content to the blood. A low glucose level may indicate a bacterial infection or tumor disease.
• Bacteriologic culture and sensitivity: CSF should be sterile. A bacterial culture can detect the presence of bacteria and determine their sensitivity to antibiotics.
• Cytology : Cytology is the microscopic examination of the cells in the CSF. It can provide clues as to the nature and origin of a disease, such as inflammation, infection or tumor disease.

Diseases of the CSF in dogs

There are various diseases that can affect the CSF in dogs. Some of these are:

• Meningitis: an inflammation of the meninges, usually caused by a bacterial infection. Symptoms may include fever, neck pain, stiffness, seizures and impaired consciousness. Treatment consists of antibiotics and anti-inflammatory medication.
• Encephalitis: An inflammation of the brain, usually caused by a viral infection. Symptoms may include fever, headache, behavioral changes, seizures and impaired consciousness. Treatment consists of antiviral and anti-inflammatory medication.
• Hydrocephalus: An accumulation of excess CSF in the brain that leads to increased pressure in the skull. The causes may be congenital or acquired. Symptoms may include an enlarged fontanel (the soft spot on a puppy's head), enlarged forehead, decreased intelligence, visual disturbances and seizures. Treatment consists of draining the excess CSF through a shunt or drug therapy.
• Spinal cord injury: Damage to the spinal cord caused by an accident, stabbing, tumor or inflammation. Symptoms may include pain, paralysis, incontinence and shock. Treatment consists of stabilization of the patient, pain relief and surgical or drug therapy.