BASICS
- Hydrocephalus is an increase in the volume of CSF, either compensatory after tissue loss or obstructive due to blockage within the ventricular system. In horses, hydrocephalus is generally obstructive
- Since CSF production is independent of CSF pressure, any obstruction of the ventricular system results in enlargement of the ventricular system within the brain
- Obstructive hydrocephalus can be observed following congenital aqueductal stenosis or may be secondary to suppurative meningitis or space-occupying lesions such as cholesterol granuloma or abscesses in older animals
- Hydrocephalus is unusual in horses compared with dogs, but it can be an inherited trait in Friesian horses, rarely in Standardbred horses, or an isolated occurrence in all breeds
- Hydrocephalus in Friesian horses has been shown to be due to an autosomal recessive nonsense mutation in a gene which in humans is associated with muscular dystrophy–dystroglycanopathy
- Systems affected—central nervous system
Acquired disease is evident at any age, but congenital disease can vary from foals born dead to developing clinical signs hours to days later.
- A history of CNS disease and/or trauma can be seen with acquired disease. However, there may be no historical association
- In foals, severe hydrocephalus can on occasion be noted as an incidental finding after sudden death due to vascular instability in the hydrocephalic brain
- Clinical signs can be very subtle even with minimal cerebral mantle remaining, but usually include failure to thrive, somnolence and aimless activity, poor suck reflex, poor swallowing, and central blindness
- Additional signs can accompany additional lesions present in individual disease types
- Just like in dogs, a ventrolateral deviation of the eyeballs can also occur. Presumably, this is the result of a change in shape and position of the bony orbits. Normal eyeball movements may be seen
- Note that Arabian foals may be born with a very “domed” head at birth but may not have hydrocephalus
Similar for the primary CNS disease processes that may be associated with acquired disease. There may be a genetic relationship in congenital disease.
DIAGNOSIS
TREATMENT
MISCELLANEOUS