Don't worry its actually quite a routine procedure. I'm surprised your foal will be sedated though, it is usually not necessary. They can be restrained quite easily without sedating them- check with your vets beforehand.
BLOODROOT CREAM!!! Its brilliant. Ive been using it for several years on various horses and types of sarcoids, its never failed to get rid of a sarcoid, and has even shifted some that the liverpool cream has failed to work on. Whats more its way cheaper (about £70) and you can apply it yourselves!
Rainbow Rider,
Its not too late to get your mare in foal, but if you want to show the foal it will be yound compared to the others, also the mare will be late foaling every year until you take a year out.
BUT, the most important thing is the STUD TERMS. The semen will be good, all frozen semen...
I would seriously consider changing vets if your vet thinks its normal for a foal to scour. Regardless whether the foal is bright and well there is a cause of the scour and your vet should be doing tests to find out what. Agree with the natural yoghurt.