Hydrocephalus may be seen in young animals (less than 18-months-old) or older animals (greater than six-years-old).
CSF is normally formed in the brain. It bathes, protects, and circulates through parts of the brain and coverings and is then absorbed into the circulatory system. In young animals, CSF can accumulate in the brain causing the fontanel (the soft spot that normally closes after birth) to bulge. The bones of the skull are soft and can be enlarged due to the increased volume and pressure leading to a dome shaped cranium. The eye position within in the eye socket may be abnormally deviated where the sclera (white portion of the eye) is visible in both eyes towards the nose.
Causes of hydrocephalus in young animals include congenital defects, intrauterine or perinatal infections, perinatal trauma, and central nervous system tumor. The most common cause of hydrocephalus in young animals is congenital defect. Toy breeds have the highest incidence.
When older animals are affected by hydrocephalus, outward signs are not as evident since the bones of the skull are already fused.
Symptoms of hydrocephalus vary with the cause, the age at presentation, the brain tissue being compromised, and the degree of tissue damage.
What to Watch For
Altered mental status
Crying out
Hyperexcitability
Extreme dullness
Coma
Seizures
Visual or auditory impairment
Spastic or clumsy walking
Circling
Head pressing
Head tilt
Abnormal eye movements
Diagnosis
Diagnostic tests are needed to identify hydrocephalus and differentiate it from other diseases that may cause similar signs.
In addition to obtaining a complete medical history and performing a thorough general physical examination, your veterinarian will likely perform or recommend the following tests:
Neurological assessment
Laboratory work assessing kidney and liver function
Skull radiographs
Computed tomography or magnetic resonance imaging
Ultrasound of the brain if there is an open fontanel present
Spinal tap (rarely performed)
Electroencephalogram (EEG)
Treatment
The goal of treatment is to minimize or prevent brain damage by improving CSF flow. Treatment depends on the severity of the clinical signs and may include one or more of the following:
Medical treatment consisting of drugs that either decrease the production of CSF or increase CSF absorption
Surgical treatment of hydrocephalus that includes direct removal of the obstruction or shunting of CSF to an area outside of the brain
Prevention of trauma such as falling or rapid changes in pressure
Follow-up examinations throughout the animal's life to evaluate any progressive brain damage and to adjust treatments
Prognosis
Untreated severe hydrocephalus has a poor prognosis and usually results in death. Although the efficacy of therapy cannot be assessed without attempting treatment, the severity of clinical signs correlates with the success of treatment. Animals with symptoms that are difficult to manage are poor candidates for medical or surgical treatment.
Some animals with congenital hydrocephalus have an immediate response to medical or surgical treatment and can be stable over a long period of time. |