Bruce offers good advice: the information is there for you to be aware of health problems in the breed and is not a list of what to expect. Nearly every breed has health problem possibilities common in the breed because the narrower gene pools from selective breeding for a purebred dog bring genetic problems to the fore over time.
However what the breeder did BEFORE you got your puppy is important: choosing the best dogs possible in health terms for parents and matching pedigrees so the right mix of genes have the best chance of coming to the fore. Artificial insemination wouldn't have anything to do with improving the good-health chances of your puppy unless the semen came from a sire who is cardiac tested and cleared, which comes from a line of cavaliers with good hearts and long lives; and ditto for good hip scores, good patellas, good eyes, and ideally, also screened for syringomyelia by MRI. Not many breeders are doing the latter yet but the numbers are steadily increasing. The same would hold for the dam.
Did your breeder show you the cardiac clearances for both parents of your dog? Also for the grandparents? Many would consider these are the most important of the various test results good breeders have for their breeding stock because MVD is the most likely condition you will see over the life of your cavalier. Also you need to realise that a puppy is a living thing and cannot be guaranteed against health problems just as a child cannot be guaranteed to have good health genes (and environment!) over its lifetime. You can improve a puppy's odds though by choosing a breeder wisely.
Any breeder should be more than willing (and often supplies as a norm) a five (or at least, three) generation pedigree with the registration for the dog (at least they do over here). This makes it much easier to research lineages and health if you are so inclined. If your breeder didn't give you this then I'd ask for one. There are online pedigree databases (I list them in the Library) and you can also work backwards from the parents if the parents are listed in the database. As Alison says,a good breeder should be happy to go through the background of your puppy, discuss the testing she performs and supply prroof of same, and also discuss the breed health concerns, so hopefully you will get a chance to do this with your breeder when she is able to come back to you.
As for the bigger breed picture:
Cavaliers DO statistically have a higher degree of problems if one goes by a fairly neutral measurment -- the number of claims filed to pet insurance companies in the UK and Ireland by breed. Cavaliers are a very popular breed, about 7th overall amongst breeds in the two countries. But they are number two for claims, according to Allianz/PetPlan. Boxers have more claims, and Westies are number three on the list.
As you probably know, there are two quite serious conditions that are prevalent in the breed: MVD and COMS, which is the comprehensive term for syringomyelia as it includes the skull malformation alone, without necessarily syrinx formation. Almost 100% of cavaliers will eventually have MVD and your breeder should have discussed this with you as most of us will eventually deal with it. As others have noted the goal is to have onset come as late as possible so that it never has any impact on your dog's health. MVD is very common in elderly small dogs but sadly in cavaliers, it is present in 50% of cavaliers by age 5 -- so everyone needs to know about this condition and its signs. Choosing a breeder who breeds for heart health is the single best way of avoiding MVD or minimising its impact. It is Russian roulette if you get a puppy from a breeder who doesn't heart test -- then that 50% chance of having a murmur by age five is the figure you are dealing with, probably considerably higher as that figure includes all cavaliers including those bred by careful breeders.
While the majority of cavaliers seem to have COMS and about 35-50-plus% in research samples have syringomyelia, right now most dogs never show any symtpoms and seem to not have it affect either their behaviour or lifespan. However it is increasing in appearance and early onset and again, it is a condition that you should know to watch for. But also be aware that the vast majority of cavaliers at this time will lead normal lives with COMS/SM and owners will never know the dog even has it.
But there is serious concern about the breed because of these two serious problems. On the MVD side, the failure of many breeders to work for healthier hearts even when selectively breeding for heart health is known to greatly decrease the incidence and severity of MVD. The cardiologist who advises the UK CKCS club has expressed deep concern that in *15 years* of having the healthy heart breeding protocol, so few breeders follow it that the incidence of MVd in the UK *has not altered at all*!! he is currently asking club members to take the problem seriously and institute a more rigorous programme of compliance:
http://www.thecavalierclub.co.uk/health/hearts/proposal06.html
Personally I agree with the many neurologists working on SM, many of whom I have been directly in contact with because I run the SM Infosite at
http://sm.cavaliertalk.com -- that this is likely a much greater threat to the breed than MVD because the long term implications -- and cost of treatment or even possibility fo treatment -- are much greater. Neurologists have reported a rapidly increasing number of cavaliers showing up with severly symptomatic SM at increasingly younger ages and this is likely to be due to the breed having reached some sort of genetic tipping point, and not likely to be due to any increase in awareness of the condition as a dog in neurological pain is going to be referred to a neurologist regardless of whether a vet recognises SM -- and neurologists who perform the surgeries for SM are seeing almost nothing but cavaliers with this condition as a genetic problem, rather than due to say a head impact.
I for one am concerned for the future of the breed and think it will take a very concerted effort from both breeders AND pet owners to make a difference. Both, because breeders make the breeding decisions, and clubs should offer if not carrots, then sticks to get breeders to breed for health... and pet owners make the vast majority of buying decisions. As long as pet owners buy dogs on the basis of cost or convenience rather than being stringent about health and making sure their chosen breeder breeds for health, the vast majority of cavaliers will come from puppy mills, mass breeder, brokers and backyard breeders, all of whom have profit and not breed health their priority. No puppy mill or BYB breeds with ANY regard for health. We as buyers need to ask for the health clearances for the conditions we DON'T want to see in our dogs or this breed generally.