Two dog breeds, side by side. Same data, no favourites.
Cavalier King Charles Spaniel
Shih Tzu
Lifespan
9-14 years
10-16 years
Size
Toy
Toy
Weight
13-18 lb
9-16 lb
Energy
Moderate
Low
Grooming
Moderate
High
Shedding
Moderate
Low
With kids
Good with kids
With supervision
What actually separates them
Less hair on the sofa with the Shih Tzu. More with the Cavalier King Charles Spaniel.
Less brushing with the Cavalier King Charles Spaniel. More with the Shih Tzu.
Calmer of the two is the Shih Tzu. The one that needs more exercise is the Cavalier King Charles Spaniel.
Shih Tzu tends to live longer — 10-16 years against 9-14 years.
With young children, Cavalier King Charles Spaniel is the safer default — Shih Tzu is listed as "With supervision".
The honest downside of each
Cavalier King Charles Spaniel
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.
Shih Tzu
That flat, 'cute' face means a genuinely narrowed airway and shallow eye sockets, so breathing trouble in heat and easily injured, bulging eyes are normal parts of Shih Tzu ownership, not bad luck.