Hydrocephalus

Hydrocephalus describes a buildup of cerebrospinal fluid within or around the brain. This fluid normally cushions and nourishes the central nervous system, but when drainage is impaired or production exceeds absorption, pressure can rise inside the skull. In dogs and cats, this may be present from birth or develop later in life, and the signs depend on how quickly the pressure changes and which parts of the brain are affected. Owners often notice changes in behaviour, learning difficulty, altered gait, or an unusually shaped head in young animals. In toy and small-breed dogs, a persistent soft spot on the skull may be palpable. Some animals live with mild hydrocephalus and show minimal signs, while others develop more pronounced neurological changes over weeks to months. This page explores the signals that may prompt concern, the mechanisms that lead to fluid accumulation, the imaging and clinical tests used to assess the condition, and the medical and surgical approaches that exist. The goal is to help you understand what hydrocephalus can look like and how veterinary teams think about it, without implying what may be happening in your own animal.