CAG is now offering a new genetic test.
Hydrocephalus is a condition found in Friesian horses, and is an accumulation of fluid in the brain. Pressure from the build-up of cerebrospinal fluid enlarges the skull of the foal. This condition is lethal, and foals are often born early. The large head size can also cause complications for the mare during foaling.
Hydrocephalus is an autosomal recessive condition, meaning that affected foals can arise when both parents are clinically normal carriers. Genetic testing allows for parents to be tested and carriers should only be bred to normal animals. Any offspring of carriers should also be tested before breeding to determine if they are also carriers.
You can learn more about the Hydrocephalus test here.