Our sheep have no problems drinking from our pond or creeks but they're usually pretty cautious about it and they don't hang out by them. But we're in central Florida and alligators are not uncommon
Not sure about lamb, but they have a real taste for dogs....there are quite a few people down there that swim with their dogs and get bit trying to rescue their pooch from the jaws of them. They snatch em right off the banks.
I'm not real sure on that, but I don't think so....at least I have never heard anyone mention it....but, I'll tag a few that have sheep that can tell ya for sure... @Baymule , @mysunwolf , @Mike CHS ....these have sheep and can answer that for sure.