A client brought in their newly purchased 8 week old pup for a check-up. It had been very quiet and started to have fits in the last 24 hours. On examination, the forehead was bulging forward and the eyeballs had slight deviation outwards and downwards.
We suspected it had a congenital condition called hydrocephalus which means "water on the brain". During development in the womb, the central nervous system (CNS), which is composed of the spine and brain, makes a special fluid that protects it from trauma and provides nourishment and lubrication. This fluid is called cerebrospinal fluid (CSF).
CSF is made in the brain. It leaves through some special channels into the spinal cord. The CNS has special areas outside of the brain where excess CSF is filtered off into the bloodstream.
In hydrocephalus, the special channels connecting the brain to the spinal cord have not developed properly and are either too narrow or absent. This means the CSF builds up in the brain and it slowly gets bigger while compressing the surrounding brain tissue. Eventually, you are left with a fluid sac in the middle of the brain that causes serious damage to the surrounding brain tissue which is pressed against the overlying bones of the skull. In a young pup, the soft bones of the skull start to bulge outwards giving rise to the dome shaped head.
Affected individuals can display all types of symptoms e.g. depression, coma, convulsions, weakness, nausea, deviation of the eyeballs.
In this case, we decided to euthanise the pup. In humans, using special diagnostic techniques like cat scans and MRI, they can place special drainage tubes between the brain and spinal cord to relieve the pressure buildup. Unfortunately, this is not available for veterinary surgeons.