The Cavalier King Charles Spaniel is a small breed of dog of Spaniel type, considered one of the toy dog breeds. It is one of the most popular breeds in the United Kingdom and has become more popular in the United States over the last ten years. It is a smaller breed of spaniel, and adults are often the same size as adolescent dogs of other spaniel breeds. It has a silky coat and commonly an undocked tail. Four colours (Blenheim, Tricolour [black/white/tan], Black and Tan, and Ruby) are recognized by the breed standard. It is a friendly, affectionate breed which is good with both children and other animals.The Cavalier shares the same history as the smaller King Charles Spaniel until the 1920s, at which time breeders attempted to recreate a spaniel resembling Charles II's King Charles Spaniel of the Restoration. The King Charles had changed drastically in the late 1600s following interbreeding with flat nosed breeds, and the Cavalier is seen as a return to the type of spaniel before that interbreeding.
There are a few health issues that affect this particular breed, most notably mitral valve disease which leads to heart failure. This will appear in most Cavaliers at some point in their life and is the most common cause of death. Syringomyelia is also present which is a malformation of the skull, reducing the space available for the brain. They are also affected by ear problems which are common among spaniels of various types as well as issues such as hip dysplasia which are common across many types of dog breeds.
The Cavalier King Charles Spaniel is one of the largest toy breeds. Historically it was a lap dog, and modern day adults can fill a lap easily. Nonetheless, it is small for a spaniel, with fully grown adults comparable in size to adolescents of other larger spaniel breeds. Breed standards state that height of a Cavalier should be between 30 and 33 cm (12–13 in) with a proportionate weight between 6 and 10 kg (10 and 18 lb). The tail is usually not docked, and is well feathered with long hair, although standards record that it should be free from curl. The Cavalier King Charles Spaniel has a silky coat of moderate length. Standards state that it should be free from curl, although a slight wave is allowed. It can grow feathering on their ears, feet, legs and tail in adulthood. Standards require this be kept long, with the feathering on the feet a particularly important aspect of the breed's features.
The Cavalier King Charles Spaniel and the English Toy Spaniel can be often confused with each other. In the United Kingdom, the English Toy Spaniel is called the King Charles Spaniel while in the United States, one of the colours of the Toy Spaniel is known as King Charles. The two breeds share similar history and only diverged from each other about 100 years ago. There are several major differences between the two breeds, with the primary difference being the size. While the Cavalier weighs on average between 6 and 10 kg (10 and 18 lb), the Toy is smaller at 4 to 5.5 kg (9 to 12 lb). In addition their facial features while similar, are different, the Cavalier's ears are set higher and its skull is flat while the Toy's is domed. Finally the muzzle length of the Cavalier tends to be longer than that of its Toy Spaniel cousin.
