A cataract is opacity or clouding in the lens of a dog’s eye which may impair a dog’s sight or cause blindness, depending upon the size and location of the cataract. Opacification of the lens obstructs light from passing and being focused on to the retina at the back of the eye resulting in vision loss. A small cataract may not be visible with the naked eye but in some cases, there may be some cloudiness seen in the eye. This cloudiness should not be confused with nuclear sclerosis which also causes clouding of the eye and is a natural result of aging. Not all dogs with cataracts will go blind or suffer any other ill effects from this condition. Size and location may determine this and a consultation with a veterinary ophthalmologist should be sought if it is a concern. It is recommended that Cavaliers with this condition should not be bred.
This is a condition where one or both of the eyes may be smaller than normal often with the third eyelid being prominent and affected eye/s being recessed. It may or may not be accompanied by another eye defect and in the Cavalier King Charles Spaniel may be accompanied by a cataract. Under North American CERF rules, one may not breed a Cavalier King Charles Spaniel with this condition but can under the UK BVA/KC eye scheme provided not accompanied by cataracts or retinal dysplasia.
The retina is the neurological structure in the back of the eye which receives light (images) and converts it to an electrical signal which transmits it to the brain for interpretation. Retinal Dysplasia is a defective development of retina where the 2 primitive layers of the retina do not fit together properly. There are 3 degrees of retinal dysplasia, folds (mild dysplasia) where there are folds in the inner retinal layer, geographic where there are larger areas of defective retinal development and detachment (severe dysplasia) where the retinal layers do not come together at all. Retinal dysplasia is a congenital defect (a dog is born with it) and does not progress as the dog ages.
While in some countries a Cavalier with retinal folds may not be bred, in North America Retinal Folds, the milder, benign form of Retinal Dysplasia are considered a breeder’s option (the breeder may choose whether or not to breed the dog) (CERF guidelines)