[Congenital hydrocephalus internus of the dog: clinical, computed tomographic and pathomorphological features of six cases].

The present study rates the value of different investigative procedures used to diagnose a congenital hydrocephalus internus of the dog. Six dogs, aged between two and ten months, were presented in our clinic with neurologic signs because of a congenital hydrocephalus internus. After taking a neurologic examination and further diagnostic studies they were euthanized and dissected. The neurologic examination did not help to predict the exact location of the lesion in the brain. Very high amplitudes and low frequencies are the characteristic electroencephalographic pattern of congenital hydrocephalus internus; they occurred in all electroencephalograms (EEGs). Radiologic changes like calvarial enlargement or thinning of the bony walls could be seen only in patients whose brain volumes had increased before the closure of the cranial sutures. The CT images of all dogs showed the dilatations of the cerebral ventricles in their entire size. Examination of the cerebrospinal fluid did not yield uniform findings. Consequently, EEG, conventional diagnostic radiography and computed tomography of the skull are the most important studies for diagnosing a primary hydrocephalus internus. However, the total extent of the lesion can be confirmed only by computed tomography. This is of special interest in case of planning and controlling therapies.