Hydrocephalus is classified into two forms—primary hydrocephalus and secondary hydrocephalus.
Primary hydrocephalus is the congenital form of the disease. It is primarily acquired while the puppy is still inside the uterus but the fluid accumulation takes place only after birth. Although hydrocephalic puppies are born normal, they will eventually manifest signs of the condition as the pressure of the fluid increases and builds-up, consequently exerting dangerous pressure on the brain. Congenital hydrocephalus is characterized by a defect in the parts of the brain which are responsible for the production and/or drainage of CSF. The mode by which the condition is transmitted to puppies has not been established.
Secondary hydrocephalus is usually acquired later in life and is often caused by infections, trauma, or other abnormalities that interfere in the normal production and/or drainage of the cerebrospinal fluid (CSF).
A cardinal sign of primary hydrocephalus is the enlargement of the puppy’s head a few weeks after birth. At this early age, the bones of the skull have not yet merged permitting the enlargement of the cranium. As the fluid continues to increase in amount inside the skull, there is a consequent build-up of pressure inside which eventually leads to the manifestation of nervous signs. This is usually observed when the puppy is about 8-12 weeks old.
Neurological signs which may be observed include seizures, head-butting, training difficulties, a characteristic eye position where the eyes are directed downwards or sometimes outwards. Hydrocephalic puppies are usually difficult to housebreak even with proper training.
Mild cases of primary hydrocephalus often tend to level off when the dog is about 1 or 2 years old and the dog may live an almost normal life. Severe cases of primary hydrocephalus will often be hard to manage.
Aside from the obvious enlargement of the head, important diagnostic tools include a CT scan or an MRI which can help assess the degree of fluid accumulation within the skull. Ultrasound can also be undertaken but the results are not as reliable compared to a CT scan or MRI.
Since it is both difficult and expensive to treat cases of severe hydrocephalus in Bulldogs or any other breed, euthanasia is the most common option or recommendation.
Symptomatic treatment can also help alleviate signs and include medication to reduce seizures and corticosteroids to address the inflammatory process in the brain. An antacid, Omeprazole, has also been recommended because it can help reduce the pressure exerted by the CSF on the brain.
A high specialized technique can also be done where a shunt is placed to redirect CSF from one part of the skull to a more benign location, such as within the abdominal cavity where the excess fluid can easily be reabsorbed. Only a veterinary neurologist or surgeon has the training and expertise to do this procedure.
A dog diagnosed with primary hydrocephalus should never be allowed to breed.