Hydrocephalus in Animals

Naturally occurring internal hydrocephalus is diagnosed in all kinds of mammals including exotic species as well as in birds. The underlying pathomechanisms are extremely variable and species-specific. In ruminants, teratogenic viruses are the main underlying cause for congenital hydrocephalus. Intrauterine infections do not play a role in equids, and the site of obstruction of CSF flow typically remains undetermined. In birds and large felids, hydrocephalus is usually acquired and often associated with vitamin A deficiency. In dogs and cats, it can be congenital but also associated with impaired skull and vertebral growth. Reduced cranial capacity impairing cerebral compliance and malformations of the craniovertebral junction (atlantoaxial instability, occipito-atlantoaxial overlap syndrome, and “Chiari-like malformation”) are the most common causes for an impaired CSF flow and communicating hydrocephalus in a high number of brachycephalic breeds. With increasing knowledge and the increasing disposition of patient owners, veterinary specialists and researchers enduringly invest in the patient management; ventriculoperitoneal shunting techniques have become a reasonable treatment strategy in dogs.