Sorry to say this on an internet site, but there are good and bad, even concerning Cavaliers or any other breed you care to name for that matter. Those who wish a breed of dogs no good will post everything negative or alarmist that they can find, while those with a genuine affection for it will concentrate on the positive. It happens everywhere.
So far as Cavaliers are concerned, I have had packs of them varying between 2 and 6 since 1983. The oldest dog I had since a few weeks old had a grade 5 murmour, for which he was medicated, and lived to 16 yrs 10 mths. You should have seen him chase a cat when he was almost 16 and he had arthritis too. His breeding partner was with him at the time and she lived to 15 yrs. The only illness she had was a pyometra when she was about 8. I kept a couple of their puppies. Easter was an amazing dog, born premature, but despite problems with her eyes, she lived to 15 years like her mother. Her mother had a sound heart until the day she died, but Easter developed a grade 2 when she was about 12 1/2. No treatment was ever needed and she walked 5 miles or so most days, staying well ahead of the pack. Then there was Victoria: now hindsight does tell me that she must have been one of the first to be affected with SM, which was late onset, because she was perfectly healthy until a couple of months before I had to loose her at 13 1/2 years. She had no murmour but an arythmic heart beat.
Of my recent dogs: Bubbles was scanned clear of SM and CM. I can't remember her having a day's illness in her life, but she could never manage to carry a litter to term. She left us a little after her 6th birthday, dying in her sleep. Her heart had been cardio checked as clear of mvd a matter of weeks before. Rebel's MRI scan at 6 years old showed a syrinx between C1 and C5. He developed symptoms about 3 years later and has been treated ever since. He is now an active pack leading little ............ into everything, who will be 12 on Saturday. He also has a barely discernable murmour which has never needed treatment. Winston Alexander is 8 years old and still a very active and healthy dog. His MRI revealed CM and he also has a slight degree of mvd, for which no treatment is required. Little Joe has been a stress related epileptic diagnosed as a young puppy. He is too afraid to walk outside on a lead but absolutely welded to his stroller, which takes him everywhere a dog can go. He has CM but no SM and no mvd, although he is now 7 years old. Holly P has Curly Coat/Dry Eye, which is an inherited defect. She was born a couple of years before AHT developed the swab test for the affective gene that we now have to prevent it's recurrence. I've just come back from the children's hospital where Holly P visits every Wednesday morning as a Pets As Therapy Dog. She brings smiles to the faces of very sick children, their carers, relatives and visitors, despite having this condition, plus an extra paw which nature gave her as a little personal bonus. She is just coming up to her 6th birthday and also with a barely audible murmour.
Up until 1992 I bred about 40 puppies from 3 different bitches. I followed almost all of them throughout their long and happy lives. None had overwhelming or life threatening health problems.
I've told you all this to show you just one so called 'hobby' breeder's experience over more than 30 years. I still show 2 of the dogs now and then, spending time talking with breeders and, sorry, I don't come across the depressing array of health problems that some places n the internet proclaim. I know of people who have had 3 in a letter with heart, eye or signs of SM problems, which is very disappointing. It is rare that I hear the stories of doom and gloom which is splashed all over the internet for everyone to read. All breeds have their own particular sets of health problems, not just the Cavalier. For the one person who compiles league table of breeds with health problems and puts Cavaliers at the top of it, there is another who uses different criteria which highlights a different breed of dog with another set of potental problems. Sorry, I just don't buy it
Surely the most important thing to do when buying any breed of dog is to check from reliable sources which health problems are prevalent in that breed and which health tests are available to prevent them, so that you can ensure you only purchase that puppy from a person who can produce the desired certificates from one or both parents. That is what gives you a greater chance of getting a healthy and long lived puppy and bears little relation to most things you are likely to find on the internet.
Sorry, I'm not talking down to you, just stating the facts as I and many others see them. All is not perfect in this or any other breed, but there are a lot of people out there doing their very best and we should try to work with them without prejudging.