There is some debate about that to be honest - if you read some of the other forums there are a few (sometimes rather hysterical) posts about hamsters being lactose intolerant. However, many experienced breeders give them milk to drink with no problems and I tend to think the experienced breeders (like those who wrote Hamsterlopaedia) tend to know more than people I don't know writing on the internet (who may just be repeating stuff they've read on the internet!).
If it worries you you could boil the milk first as this, apparently, boils of the lactose content.
As for soya milk I've no idea - hopefully someone else can help!
|