People will know I take a firm stance on this issue but will argue the point again.
I strongly believe that setting minor changes in a dog's appearance against an increased lifetime risk of mammary cancer or a possible coat change is a discussion that HAS to come down on the side of health, not appearance. Think about what is being discussed! -- how are such decisions any better than what many here rightly condemned about dogs bred for appearance, not health?
A 7% lifetime risk is a very significant risk and the highest health risk factor in the debate, such as it is, between spaying or not to spay,or to delay spaying -- the risks associated with neutering are TINY compared to the 7% risk for females after first heat and the whopping 25% risk after two heats! -- a one of four chance of cancer -- far higher than the lifetime risk for woman of breast cancer. The change in appearance is highly subjective anyway -- females don;t change much at all to become 'more feminine' -- set against the fact that male cavaliers are not the most masculine looking male anyway, and I've had intact males referred to as 'she' by people that meet the dogs, so who cares? Not the dogs :lol
, At any rate your dog's appearance and how 'correct' it appears is almost entirely going to depend on its background and lineage, and whether the breeder is a show breeder, not whether it gets spayed or neutered at any particular age. And only a tiny proportion of the world is going to know what a correct female or male head or body should look like in the breed -- and this too is highly subjective and has changed utterly over time (I have a 1960s book in which the breed looks far more springer-like!) -- so does this truly matter?
The idea that females benefit from a first litter hasn't been taught in vet schools in well over a decade now because cancer risks are better understood. In addition the mortality risk from a pregnancy is perhaps the highest death risk a female dog can suffer. And as any unexpected pregnancy is likely to produce cross puppies that just add to the roster of unwanted puppies that can be very difficult to rehome, that's a death risk to the puppies as well -- or a burden to a rescue or pound that is left trying to home them or putting them to sleep as unhomeable.
Most of the dogs that I and friends in rescue have had come in with serious medical problems (that are not heart related, in my case) are directly related to the fact that they are intact still --cancerous testicles, prostrate problems needing surgery, mammary tumours. Most of the serious problems I have known in females outside SM or MVD is pyometra. According to one Swedish study of insurance records, the risk for pyometra in this breed is considerably higher than normal -- over 40%.
Six months is the generally recommended age at which to spay and most females won't come into heat at this age, so there's no fault or blame for a dog that surprisingly goes into heat -- just be sure to manage it carefully, then arrange for a spay three months after it ends.