Cavalier King Charles Spaniel vs Miniature Pinscher

Heart disease isn't a risk for Cavaliers so much as a near-certainty — about half develop a heart murmur from mitral valve disease by age 5, and veterinary sources note that essentially every Cavalier that lives long enough will eventually develop it, making it the breed's leading cause of death.

Despite the nickname 'King of Toys' and a look that leads many buyers to assume it's a scaled-down Doberman Pinscher, genetic and historical evidence indicates the Miniature Pinscher is an older, separate breed with no close ancestral link to the Doberman — and its actual temperament is fearless, high-energy, and independent, closer to a terrier than a typical toy lapdog.