In KY not very common at all. The farms, esp one of Hill N Dale’s stature are set up to deal with just about anything that can go wrong with the average foaling. In my personal hands on experience things don’t go “wrong” very often. IMO foaling is one of easiest and non eventful things that horses do 95% of the time. When things go wrong with the other 5% they generally go very wrong. Even with vets on site.
This is a very valuable mare in foal to a top very expensive stallion. With a history of difficult foaling. Which is why she was sent to the clinic.
As LaurieB said cracked/fractured rid/s are not uncommon but they are not very common IME foaling out lots of mares. Personally never had one. Lots of other things but not that.
I have known the owner of Hill N Dale for over 30+ years. Knew his father and did a far amount of business with him. He was killed in a tragic accident a long time ago. His horse business was not his principle business in Canada. John and his brother Glen took over things. Glen stayed in Canada running the original Hill N Dale. John started the Ky division on a much smaller scale. They, John bought the present farm which was called North Ridge when the wealthy owner who built it left the business. BEAUTIFUL farm, couldn’t build it for what it was bought for. Not even close.
John is a tough cookie, shrewd no nonsense businessman. But not one to play the lawyer card at the drop of a hat.
That being said, we are only hearing one side so far. Unless settled out of court. There will be public record, reporting of both sides. Which will make for interesting, educational reading.