Question: What kind of animal is the Yorkshire Terrier and the Cavalier King Charles Spaniel?

Context articles: King Charles Spaniel
Canine Chiari-like malformation
Toy Trawler Spaniel
Cavalier King Charles Spaniel
Rex (dog)
Beaglier
Yorkshire Terrier
Dash (spaniel)
Huddersfield Ben
Cavapoo

The King Charles Spaniel (also known as the English Toy Spaniel) is a small dog breed of the spaniel type.
 In 1903, the Kennel Club combined four separate toy spaniel breeds under this single title.
 The other varieties merged into this breed were the Blenheim, Ruby and Prince Charles Spaniels, each of which contributed one of the four colours available in the breed.
Chiari-like malformation (CM) is the most common cause of foramen magnum obstruction and syringomyelia in dogs.
 Syringomyelia (SM) is a disease of the spinal cord typified by fluid filled cavities, or syrinxes, within the spinal cord substance.
 The disease is caused by the obstruction of cerebrospinal fluid (CSF), in the nervous system.
 A situation of high pressure in the spinal cord compared to low pressure outside, leads to fluid accumulation, which eventually forms cavities.
 CM is a condition characterized by the mismatch of size between the brain and the skull.
 The skull is too small causing part of the brain to descend out of the skull through the opening at its base, crowding the spinal cord.
 The cause of CM is not yet fully understood.
 CM is rare in most breeds but reportedly has become very widespread in the Cavalier King Charles Spaniel and the Griffon Bruxellois (Brussels Griffon).
 Some researchers estimate that as many as 95% of CKCSs may have CM.
 It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the Cavalier King Charles Spaniel.
 CM is so widespread in the Cavalier that it may be an inherent part of the CKCS's breed standard.
 This disease not only affects thousands of dogs, but a similar condition affects over three hundred thousand children yearly.
 Therefore, canines are an appropriate model for the treatment of the human condition.
The Toy Trawler Spaniel is an extinct breed of Spaniel which physically was similar to the King Charles Spaniel of the 16th century.
 It is considered to have descended from the original King Charles Spaniel, and the older variety of Sussex Spaniel.
 It was originally used as a sporting dog, but became used as a toy and show dog.
 It was considered to be on the verge of extinction by 1920.
 A preserved specimen is kept in Tring at the Natural History Museum.
The Cavalier King Charles Spaniel is a small spaniel classed as a toy dog by The Kennel Club and the American Kennel Club.
 It originated in the United Kingdom and is one of the more popular breeds in many countries.
 Since 2000, it has grown in popularity in the United States and ranks as the 18th most popular pure-breed in the United States (2013 Registration Statistics).
 It has a silky, smooth coat and commonly a smooth undocked tail.
 The breed standard recognizes four colours: Blenheim (chestnut and white), Tricolor (black/white/tan), Black and Tan, and Ruby.
 The breed is generally friendly, affectionate and good with both children and other animals; however, they require a lot of human interaction.
 Since they are a family dog, it is recommended to not leave them alone for long periods at a time.
 The expected average lifespan of a Cavalier King Charles Spaniel is under ten years.
Rex (December 16, 1984 – August 31, 1998) was a Cavalier King Charles Spaniel owned by Ronald Reagan and his wife Nancy during his term as President of the United States.
The Beaglier is a designer breed, the offspring of a Beagle and a Cavalier King Charles Spaniel.
 The Beaglier became particularly popular through crossbreeding programs in Australia during the 1990s.
 The dog was developed because of affection for the Cavalier King Charles Spaniel and the Beagle breeds; the breeders were looking for a healthy, energetic small dog with a less active scent drive than that of the Beagle.
 They are very popular in Australia due to their temperaments.
 The Beaglier typically has the shorter and more rounded muzzle of the Cavalier.
 Beagliers have variable coat colours and markings.
The Yorkshire Terrier is a small dog breed of terrier type, developed during the 19th century in Yorkshire, England, to catch rats in clothing mills.
 The defining feature of the breed is its maximum size of 7 lb , although some may exceed this and grow up to 15 lb .
 It is placed in the Toy Terrier section of the Terrier Group by the Fédération Cynologique Internationale and in the Toy Group or Companion Group by other kennel clubs, including the American Kennel Club.
 A popular companion dog, the Yorkshire Terrier has also been part of the development of other breeds, such as the Australian Silky Terrier.
 It has a grey, black, and tan coat, and the breed's nickname is "Yorkie".
Dash (1830–1840) was a Cavalier King Charles spaniel owned by Queen Victoria.
 Victoria's biographer Elizabeth Longford, called him "the Queen's closest childhood companion", and in the words of the "Oxford Dictionary of National Biography", he "was the first in a long line of beloved little dogs".
Huddersfield Ben (c. 1865 – 23 September 1871), an early Yorkshire Terrier, is universally acknowledged to be the foundation sire of the breed.
 In his day Ben won many prizes, both as a show dog and in ratting contests.
 He had tremendous influence in setting the breed type for the Yorkshire Terrier, a new breed still under development in Ben's day.
 Although larger than a standard Yorkshire Terrier, Ben regularly sired stock under 7 pounds.
The Cavapoo (also known as a Cavoodle) is a crossbreed dog, the offspring of a Poodle and a Cavalier King Charles Spaniel.
 The Cavapoo became especially popular through crossbreeding programs in Australia in the late 1990s.
 The Cavapoo has since become one of Australia's most popular breeds.
 Cavapoos were bred by ACA Breeders kennels to be healthy, outgoing, small dogs with a low to non-shedding coats, who would get along well with children.
 They are a very popular crossbreed dog in Australia due to their exceptional temperaments, robustness and low-shed.
 The breed is also increasingly popular in the United Kingdom.