Sporadic cases can occur in any breed, but it is most common in small and toy breeds. If hydrocephalus occurs in a puppy there is usually an abnormally large, dome shaped head. If hydrocephalus occurs after the skull has stopped growing, the head will not enlarge. Hydrocephalus can cause a variety of neurologic signs, including seizures , incoordination, abnormal behavior, a tendency to walk in circles, and blindness. These signs may wax and wane or become worse over time.
Diagnosis is based on the signs in conjunction with techniques to image the brain.
In dogs with a fontanel, ultrasound can be performed by scanning through the fontanel to detect the excessive accumulation of fluid within the brain. Young dogs with mild signs may improve without treatment as they get older. Medication, such as corticosteroids, are sometimes helpful. In some cases, surgery is performed to implant a ventriculoperitoneal shunt. This is a device that transfers the excess fluid from within the brain to the abdomen, where it is absorbed.