Aga,

I grew up in europe and I have never seen any 4h horse trailers, always horse vans/trucks on Iveco/Renault/Mercedez chassis...they will obviously be more expensive and perhaps require a different driving license.

Also, there aren't many vehicles in Europe that would be a able to tow such a big trailer (unless you are importing a pick-up): they do have Range Rovers (diesel), Land Cruiser(diesel) and even Escalades (gas engines) but they won't be cheap.

Europe is kind of big: which country are you based in?

Also look at this:

http://www.polocenter.com/tranport/trailers.htm

Aga,

I found this in England, but it's a bumper pull....http://www.agrimark-trailers.co.uk/horsetrailer-cheval4000.php

or this one is germany (a little cloder to Poland...)http://www.boeckmann.com/_eng/wueu_pferde_eng_17912.html

another option you might have would be to get a boat trailer (a long one) and build a box on top of it...

I sold 3 trailers to a guy in Austria last summer.They were 4 Horse and were built for the road laws over there.I can set you up with him if your interested?He is a dealer .