Cavalier King Charles Spaniel

The lovely Mina, owned by the family of a friend of mine. She is red and white, a color combination that is called "Blenheim" in the Cavalier.

The Cavalier King Charles Spaniel is one of the most social and lovable dog breeds. Their tail constantly wagging, never saying no to a walk, whether it's a trip around the block or a long hike in the mountains, the Cavalier is jolly all the same. Like all other spaniels the breed started out as gun dogs, but due to their size and their temperament, they soon proved popular as companion dogs. The Cavalier became a recognized as a breed by the kennel club in 1945, but the type had its own standard as early as 1928 and was then called "King Charles Spaniel, Cavalier type". The King Charles Spaniel is a much older breed, and toy spaniels like the King Charles Spaniel has been linked to the English royalty since the mid 1500s.

During the second world war, most Cavaliers were lost. And at the end of the war, only 6 cavaliers were known to be in existence. These six became the base for the restoration of the breed, a bottle neck in the lineage with severe consequences for the general health of the breed. Most Cavaliers today have serious health issues, individuals being de facto as closely related as siblings.

Despite the generally poor health, they have one of the best temperaments of any breed. You will seldom encounter an aggressive Cavalier. Even when in substatial pain, they'd rather avoid conflict than bite you. They are truly lovable dogs, often described as great family pets and an excellent choice of breed for first time dog owners.

The wonderful Cooper, my boyfriend's family's Cavalier, was a Tricolor, although he had very indistinct brown markings.

Health

If you are looking for a healthy dog that will live a long life, you should probably find another breed. Almost all Cavaliers are prone to heart disease, and many have a serious neurological condition called Syringomyelia. Syringomyelia (SM) is a disease caused by the deformed skull in brachycephalic breeds with domed skulls, which basically leaves inadequate space for the brain. In humans it has been described as extremely painful and normally non painful stimulus like wearing a t-shirt or getting a hug can be an excruciatingly painful ordeal. Affected dogs will often be seen scratching in the air next to their neck, especially when excited, suddenly whining or yelping without apparent reason. A study of 555 cavaliers with, according to their owners, no clinical signs of SM, showed that as many as 70% of Cavaliers aged 6 years or older had SM. (Source)
Mitral valve disease (MVD) constitutes the most common heart defect, and whilst relatively common in many breeds, the onset of the disease is predominantly earlier in the Cavalier.  It can be detected as a heart murmur, and can lead to heart failure and subsequent death. 90% of Cavaliers at age 10 have developed MVD, but only about 30% of these get heart failure and die from this cause. (Source)
Cavaliers also suffer from a number of eye conditions. The most common ones are congenital cataract, juvenile cataract and retinal dysplasia. According to Wikipedia, as many as 30% of all Cavaliers suffer from an eye problem. Like most spaniels, ear infections also constitute a common problem. For some of the prevalent eye and ear problems, an underlying allergy or autoimmune reaction might be the cause.
As if these medical problems weren't enough, the Cavalier prevalence for hip dysplasia (HD) and luxating patella (PL) is a concerning factor. According to the Orthopedic Foundation for Animals, 12.5% of Cavaliers have HD and 2.1% has PL. While these issues aren't particularly frequent in comparison to other breeds, stock animals should still be checked before use in breeding. They should also have their eyes and heart examined and be scanned for SM.
Another health issue, too often neglected, is dental health. The Cavalier, being a brachycephalic (short snout) breed, often has very little space in which to fit all of its teeth. They are therefore prone to periodontitis, an inflammation of the gums which may lead to loss of teeth if left untreated. Periodontitis may lead to a number of derivative complications in the rest of the body, as this constant state of inflammation can expose the animal to bacteria derived from the oral cavity and spread through the circulatory system. This can cause heart and kidney problems. Fortunately there is a cheap and easy way to avoid dental problems in any dog; Train your dog to tolerate having its teeth brushed from an early age, and especially as a Cavalier owner, you will save a fortune in dental work at the vet, and more importantly, vastly improve the well being of a dog that loves you unconditionally. 
When you get a Cavalier, make sure to insure it well, as the chances are slim that your Cavalier has none of the known medical conditions prevalent in the breed. You should always get insurance for your dog, no matter the breed, but the long term medical costs for the Cavalier is not likely to come cheap, so it is extra important when getting a Cavalier. Make sure to check what the insurance will cover avoiding any unpleasant surprises down the road.

he main inherited genetic eye conditions in Cavaliers are cataract (Congenital and Juvenile), and multifocal retinal dysplasia. - See more at: http://www.thekennelclub.org.uk/services/public/breed/health.aspx?id=6149#sthash.2LdVMTm4.dpuf

he main inherited genetic eye conditions in Cavaliers are cataract (Congenital and Juvenile), and multifocal retinal dysplasia. - See more at: http://www.thekennelclub.org.uk/services/public/breed/health.aspx?id=6149#sthash.2LdVM

This cavalier I met at a dogshow in Tromsø in june 2011, is an example of a black and tan dog.

Training

Cavaliers are easy to train, and will be good at many dog sports as long as they are healthy enough to participate. Obedience, agility, heelwork to music/freestyle are all dogsports which may suit your Cavalier. Being a spaniel, with roots as a gun dog, they may with training serve as retrievers of small game, though hundreds of years of breeding for companion dogs have definitely taken its toll on their natural ability. Most of them will display a certain prey drive for birds during walks, though what they'd do if they caught up with one is anyone's guess. Most Cavaliers serve simply, and impeccably, as companion dogs, a life that suits this laid back and happy dog. They prefer to always be with you, so don't get a Cavalier if you have to leave it alone at home for most of the day. Like all other dogs, the Cavalier benefits from regular exercise and mental stimulation. Most Cavaliers are excellent with small children, though as usual, I would never advocate leaving dogs unsupervised with them, regardless of breed. Though they can be cool as a cucumber sleeping on a couch or their bed, they are grateful for any opportunity to play and train, however, their attention span can sometimes be described as wanting. Short bursts of training coupled with play and excessive cuddling could make you as good of a friend to your Cavalier as he or she is to you. They enjoy tracking for hidden treats, a sensory and mental stimulus suitable for winter nights when two hour walks are out of the question.

Sara is a Ruby Cavalier.

If a happy-go-lucky companion is what you are after, the Cavalier might just be the dog for you. Though the dog is no longer primarily associated with royalty, proper medical care could prove a costly affair for the average person. I therefore strongly recommend a well researched and sturdy insurance scheme, as well as an ample fund for regular and professional dental care unless you are qualified and committed to provide this yourself. Substantial costs are associated with the medicinal management of heart and neurological conditions. Treatments will be worth every penny, just make sure you can afford them before getting your Cavalier, and be aware that the conditions are very likely to arise. You'll never have a friend as true as the Cavalier, make sure you can reciprocate the dedication and care you'll receive.

PS: If I seem negative towards the breed, it is solely out of concern for the fate of the individual dogs' well-being. Cavaliers make us want to take care of them and love them, but that may also cause potential dog owners to get one before having thought it through. Cavaliers demand special care, and getting one without knowing both what concerns there are, and how well equipped you are to serve their needs, is a rash decision, which may lead to unnecessary suffering for the dog.