The Cavalier can need from 18 to 24 months to reach maturity. Hair stripes, intense color and complete body development arrive in time, to complete the potential show dog.
An active, graceful and perfectly balanced miniature spaniel, the Cavalier King Charles Spaniel stands between 30 and 33 cm and weighs between 6 and 9 kg. The skull is practically flat between the ears, and the stop is light. The eyes are large and dark, well separated, but not prominent; the ears, long, high inserted, and well provided with long hair. The neck is moderate length, slightly arched; the chest, moderated; the shoulders well sloped backwards; the limbs straight and moderated bones. The tail is proportional to the body length, and carried cheerfully, but not over the back. The coat is long and silky, with abundant stripes, never curly – a slight wave is allowed. Traditionally the Cavalier exists in four colors: black and tan, solid red (ruby), Blenheim (white and red); and tricolor.
Most Cavalier King Charles owners are addicted to these pretty dogs, and have two or three. Why not? They are small, clean and graceful. They allow spoiling, and lead the obese life with royal elegance. Sleeping at the master’s bed and drinking from the owners’ cup are usual things in the Cavalier’s homes. It is active and affectionate, of the most derisive, proceeding from England (where it is praised as one of the most popular breeds). An apartment dog by excellence, it is very polite, and easily learns to relieve itself on the newspaper.
Don’t overfeed the Cavalier puppy. The breed has a healthy appetite and loves to eat whatever it can find. Obesity, the plague of the toy breeds, makes many more victims amongst the spoiled Cavaliers. 
The puppy’s weigh varies according to the litter size, the puppies in small litters usually weigh more and get larger as adults than numerous litters (six or more puppies). The Cavalier puppy has a sweet tooth, and the owner should supervise and provide a strict diet, without too many snacks or food remains. The puppy should also make a lot of exercise and outdoor activities. The Cavalier should be kept as a small sporting dog, not as a delicate toy. Both testicles should have descended completely after eight weeks, although it can take up to six months. Inferior prognathism is frequent, although it can be corrected on its own towards 18 months; however, when choosing a puppy, we should avoid unlevel bites.
The Cavalier puppy can weigh only 1.5 kg when you take it home. It is delicate and affectionate, and it needs your loving and soft care.
The Cavalier is relatively exempt of serious anomalies. The most important thing is eye, ear and skin care; otitis is very common, in part due to dropped and long ears. A type of dandruff is frequent during adolescence. Diet should be based on prescriptions by the breeder or veterinarian. Some heart problems are reported, including a murmur at six years, as well as a serious hereditary anomaly that is usually mortal. An unusual hallucination anomaly has been registered, commonly known as “flycatcher” (without there being flies). Not much is known about it. The Cavalier is long lived (the average is 9 years, maybe 13 or 15, exceptionally to 19) and healthy, with minimum hair care and moderate demands as for exercise. Trimming is forbidden in the Cavalier, and only the hair between the limb pads should be cut. For the rest, it only requires brushing several times per week.
The Cavalier puppy of your choice should have clean and shiny hair. Be careful, which can suffer dermatitis and otitis from the four months.