The Cavalier King Charles Spaniel is a small breed of dog. The breed was developed by selective breeding of long-snouted King Charles Spaniels (also known as English Toy Spaniels). The development of the Cavalier King Charles Spaniel was partly due to a desire to produce a long-nosed toy spaniel, as are seen in the paintings of the great masters. Long-snouted toy spaniels no longer existed at the beginning of the 20th century, due to crosses between long-snouted toy spaniels and short-snouted breeds such as the Pug or Japanese Chin in the 18th-19th century.
The breed has four recognized colors: Blenheim (reddish brown and white), Black and Tan (black and reddish brown), Ruby (reddish brown), and Tricolor (reddish brown, black and white).
The breed is highly affectionate, and some have called the Cavalier King Charles Spaniel 'the ultimate lap dog'. The dogs require a great deal of human companionship, and do not do well if left alone for long periods of time. The breed suffers from a number of congenital defects, most significantly, mitral valve disease. This condition can begin to emerge at an early age, and is present in many Cavalier King Charles Spaniels by 5 years of age. Responsible breeders are attempting to breed only from dogs that exhibit a later onset of the disease. The increasing popularity of the breed has led to breeding of the Cavalier King Charles Spaniel in puppy mills. Those interested in purchasing a Cavalier King Charles Spaniel should be very cautious about selecting a breeder and should never purchase this breed from a pet store.