Hydrocephalus is a common congenital (existing at or dating from birth) or acquired neurologic disorder in dogs and cats. Hydrocephalus is excessive accumulation of cerebrospinal fluid (CSF) in the brain. CSF is produced in the brain at a slow rate all of the time. Normally, it flows freely around the brain and spinal cord, but if there is an obstruction to the flow of this fluid, it can accumulate and cause compression of the normal brain structures. Hydrocephalus usually results from a congenital narrowing of the mesencephalic aqueduct (the passage for drainage of CSF from the brain). Thus, CSF begins to build up and cause compression of the brain, even before birth. Although a differential diagnosis (thedistinguishing of a disease or condition from others presenting with similar signs and symptoms) for the disorder exists, the underlying cause of congenital hydrocephalus is often unknown.
Hydrocephalus may occur in any dog or cat, but it is most commonly found in toy breeds (Chihuahua, Yorkie, Maltese) and in brachycephalic, or short faced, breeds (such as English Bulldog, Pug, French Bulldog). When it is severe, the symptoms begin within the first few months of life. More moderate or mild cases may be asymptomatic (showing noevidence of disease) or may only begin to show symptoms as an adult.
More about CSF:
The primary function of CSF is to provide physical protection for the brain and spinal cord from mechanical forces. These forces may arise externally from traumatic blows to the head or vertebral column or internally from acute changes in intravascular volume. The CSF provides a buoyancy effect for the central nervous system because the specific gravity of CSF is lower than that of brain tissue. Suspension of the brain in a liquid environment reduces its weight. CSF also nourishes neural tissue through distribution and movement of various proteins, molecules, and ions.