Oh Helen, I'm so sorry. I know exactly how you feel, I had the exact same thing happen with a mare last May, only with ours the placenta passed out normally once we got the foal out so we didn't have that worry.
I pray that Katie will be okay--you know how much I like that little mare! She will be feeling pretty rough for a few days--our mare took a week to start looking less sad, and after 2 weeks she was pretty much back to normal. I sure hope Katie will be the same.
I'm just so sorry you had to experience this with Katie, and also sorry to hear about your dog. {{{hugs}}} to you.
Holly