It is known that HC is inherited by and automal recessive path (i.e. both parents must be carriers of the defective gene to produce and affected offspring). HC is a progressive condition and this means that although a puppy is not born with cataracts they will start to develop at a juvenile age. (maybe from 8 months onwards), and will progress until the dog is totally blind. This condition is bilateral which means is affects both eyes equally. Thanks to the tireless research by the Animal Health Trust in Newmarket there is a now a DNA Test for Hereditary Cataracts.