The Cavalier is a wonderful companion. However, the new owner needs to be aware that MVD (heart disease) is a major health concern for the breed. The new puppy buyer needs to insist on seeing current health clearances for the sire and dam. These include: hearts, eyes, hips and patellas. Some breeders are also testing for Syringomyelia and EF/CC/DE. A good breeder will take the time to answer any and all concerns. Start a conversation.
Great resources about the Cavalier:
The AKC- American Kennel Club: www.akc.org
The CKCSC, USA - Cavalier King Charles Spaniel Club (the original breed club): www.ckcsc.org
The ACKCSC - American Cavalier King Charles Spaniel Club: www.ackcsc.org