Hi and welcome! And I echo that thanks for taking the time to look for a health focused breeder. You're asking some big questions, but the right ones. It has always frustrated me that farmers take more care to avoid genetic bottlenecks to keep their stock healthy, and to preserve rare breeds and that zoologists do more work towards saving species through careful breeding programmes, yet dog (and increasingly cat) breeders have no restrictions on what animals they breed and what health problems they produce for animals that, compared to most farm stock, will live much longer and potentially suffer much longer. In 25 years I've seen how few cavalier breeders really focus on health. Yes some sperm is brought in from other countries but mostly the focus is on improving winning show traits
. However some import for health too. Other countries screen and indeed there is also legislation in some countries such as the Netherlands and some Nordics regarding breeding and -- due to breeders being unable to show they were taking adequate steps to address heart and CM/SM health in Norway -- breeding cavaliers is banned there completely now due to a case that went to its highest court.
Things are likely to shift towards more breeding requirements in the UK and the EU; I've been to national kennel club meetings (in Ireland) where the likelihood of this happening has been stressed to breeders (in part by a key UK Kennel Club individual). Breeders continue to dispute the scientific evidence that health testing and following breeding protocols improves health even when statistics from such programmes show it to be true. They'll claim dogs are 'cherry-picked' for positive or negative testing result and so on and I've seen a shocking level of abuse and defamatory statements thrown by well know breeders at researchers who are trying to help save affected breeds, over the years.
There is a carefully planned outcrossing programme for cavaliers to try and improve genetic diversity. Experts have stressed you can't just cross to another random breed and especially not to breeds of similar size and background (like other toy breeds) because the same genes for the same issues are there (thus the claim that 'designer crosses' like cavachons are healthier simply is not true). There is a carefully planned and genetically supervised CKCS outcross programme underway to beagles in Finland. You can read more here:
https://www.facebook.com/CavalierMa...tter-to-a-beagle-is-now-a-ye/889052123247854/ Beagles were chosen because of the genetic distance from cavaliers, The first generation look like beagles, as the short coat is dominant, but this should moderate over a few generations. There is at least one other person crossing to beagles abroad but this seems to be a go-it-alone project and not sure the puppies are retained or sold to homes (?) and without some oversight and genetic testing involved I'd worry that this is... not helpful. But we'll see. Needless to say the Finnish project is controversial in some corners but as breeders keep selecting to breed within narrow lines much potential genetic diversity has been long lost in the past three decades even when breeders knew such diversity was likely to be important. Key to note, too, that what the UK Kennel Club lists as the inbreeding quotient officially for a given dog is probably way, way off. Actual genetic testing has shown considerably less genetic diversity and at times, double to triple the inbreeding coefficient.
So adequate diversity coupled to health over time is now probably impossible with existing lines. That said many breeders really work to get the best diversity and health they can as next steps are considered for the breed.
