Indy is an eleven week old Vizsla puppy with an obviously enlarged and somewhat rounded head. MRI confirmed the clinical suspicion of hydrocephalus. Note the dramatic dilation of the lateral ventricles with minimal remaining cortical tissue.

Hydrocephalus is an enlargement of the cerebral ventricular system secondary to an increased amount of CSF. Excessive CSF may be the result of obstruction to flow (non communicating or obstructive hydrocephalus), poor absorption, or increased production (communicating hydrocephalus). Most cases of hydrocephalus seen in veterinary medicine are congenital. Numerous breeds are at an increased risk of hydrocephalus including Maltese, Yorkshire Terrier, Toy Poodle, Cairn Terrier, English Bulldog, Boston Terrier, Chihuahua, Pug, Lhasa Apso, Pekinese and Pomeranian.

Young animals with hydrocephalus usually are smaller and less developed than their littermates. They are often depressed, have episodic behavioral changes such as aggression or confusion, and frequently have seizures. Their mental development is retarded, so they do not learn as readily as their littermates. Visual deficits are common due to damage to the occipital cortex. Motor function may range from an almost normal gait to severe tetraparesis.