Many things which have been allowed in the USA are quite specifically banned in the UK, for example declawing of cats
1 which seems almost routine for USA cats living in apartments, wouldn't be allowed in the UK (at least not just for the purpose of saving your furnishings).
Crate training of puppies seems common enough in the USA, but talking to someone at the Blue Cross about it, they reckoned it would likely be considered an offence in the UK (or at least enough to get you charged with cruelty).
On the other hand, things like cross breeding dogs with close relatives seems common enough in the UK, although it seems like a really bad idea from a genetic standpoint.
Footnote 1 : Not really declawing, more equivalent to amputating the final bone of their claws.