Symptoms of Hydrocephalus (Water on the Brain) in Dogs

Source: PetWave, Updated on July 16, 2015

How Hydrocephalus Affects Dogs

Dogs with hydrocephalus usually show symptoms of degenerative neurological disorders, which are referred to as “encephalopathies”. It is difficult to speculate as to how “water on the brain” actually makes an affected dog feel. However, we can extrapolate from what owners observe – and from what people with hydrocephalus report - that it is an uncomfortable, frightening, often painful and potentially life-threatening condition, especially when pressure inside the skull increases to dangerous levels.

Symptoms of Hydrocephalus

Owners of dogs that are born with hydrocephalus or that acquire the condition during their lives may never notice signs of their dog’s disorder. This is especially true in toy and miniature breeds. When symptoms are present, owners may observe one or more of the following:

  • Domed skulls (high, rounded heads)
  • Mental dullness
  • Disorientation
  • Dementia
  • Lack of coordination (ataxia
  • Lethargy
  • Excessive tiredness and sleepiness
  • Hyperexcitability (+/-)
  • Changes in mentation (decreased awareness of familiar people or surroundings; others)
  • Behavioral changes
  • Compulsive behaviors (tail-chasing, circling, abnormal vocalization; others)
  • Aggression
  • Head pressing
  • Stunted growth
  • Respiratory difficulties
  • Changes in stride or gait
  • Changes in posture or stance
  • Inability to learn normally; lack or loss of apparent ability to behave as already trained (regression of housetraining; inappropriate elimination; others)
  • Abnormal eye position (eyeballs rotated down and outward; ventrolateral deviation of the orbits; ventrolateral strabismus)
  • Vision abnormalities (partial to complete blindness)
  • Aimless wandering
  • Stupor
  • Coma
  • Seizures
  • Death

The nature and severity of a dog’s symptoms may not necessarily correspond to the degree of enlargement of its cerebral ventricles caused by the increased accumulation of cerebrospinal fluid. In other words, a dog with mild fluid build-up inside of its brain may show severe clinical signs, while a dog with significant accumulation of CSF may display only mild or even no signs of its condition.

Dogs at Increased Risk

Congenital hydrocephalus is fairly common in some toy and brachycephalic breeds – especially in Chihuahuas, whose domed skulls are considered to be a desirable conformational trait but also predispose the breed to developing “water on the brain.” Toy Poodles, Lhasa Apsos, Pugs, Pomeranians, Pekingese, Maltese, Shih-Tzus, Bulldogs, Boston Terriers, Yorkshire Terriers, Manchester Terriers and Cairn Terriers are also predisposed to congenital hydrocephalus. Other factors that reportedly may be associated with hydrocephalus are small birth size of individual puppies, stressful whelping (dystocia in the dam) and short pregnancies. Normal adult Beagles have a particularly high incidence of enlarged ventricles with excess pooling of cerebrospinal fluid but without any noticeable symptoms of illness. Acquired hydrocephalus can happen in any breed of dog. There is no known gender predisposition for canine hydrocephalus. Congenital hydrocephalus typically is noticed by one year of age; acquired hydrocephalus can occur in dogs of any age.

Dog Health Center


Cancer in dogs is defined by the uncontrolled transformation of normal cells into abnormal ones, which usually form masses, invade nearby tissue, and ultimately spread.

Learn more about: Cancer