Generally speaking the Cavalier King Charles Spaniel is a fairly healthy breed of dog - providing you obtain it from a reputable breeder. It is always a good idea to be able to have some understanding of your dog's heritage as it could point to a predisposition to certain diseases. For example, it used to be said that the Cavalier King Charles Spaniel had very good eyesight. Although with all dogs eyesight can dim when they get older and the Cavalier King Charles is no exception. In the last fifteen years or so this has changed and some Cavalier King Charles Spaniels are more susceptible to eye disease.
In a survey undertaken in 1989 it was estimated that forty percent of Cavalier King Charles Spaniels may suffer from hereditary eyesight problems - especially retinal dysplasia. This is the most serious of the eye diseases that can affect this breed and it is due to a problem with the formation of the retina. Sometimes this appears as what is known as retinal folds and may go unnoticed by the dog apart from occasional blind spots. Some Cavalier King Charles Spaniels however can end up completely blind. The only thing that you can do is to make sure when you get your dog that you check out their parentage. A good breeder will be able to tell you if your dog might be disposed to these problems with their eyesight. In Britain breeders would have their dogs checked by a veterinary ophthalmologist who would recommend that any dog with this particular problem should not be bred. This is why you should always get your dog from a reputable and well known breeding kennels as they will adhere to these rules. It is not usually said that a dog with the mild form of retinal dysplasia discussed here should not be bred.
The Cavalier King Charles Spaniel is a beautiful dog but like most other dogs they need looking after in ways that are particular to their breed. Hopefully your dog will not have troubles with the retina and should not suffer significantly from eyesight problems until he or she is much older. However, most dogs will at sometime in their lives suffer from conjunctivitis. When this happens you should bathe your dog's eyes regularly to keep them clean and to clear away the mucus. If the problem persists then you will need to take your dog to the vet. The thing that most vets prescribe is very akin to the golden eye ointment that you might use on a child with conjunctivitis. Apply it regularly, and keep the eye clean and this should not significantly affect your dog's eyesight. If the conjunctivitis is left however, then it could cause permanent eye problems.