I've just had stuff shipped from Africa into Prestwick. I am well aware, before we get the smart Alec replies, that you live in Wales and your question was regarding a boar in Portugal, but if you pm me I'll give you the name of the shipping company up here. I can't imagine it matters to them which airport it comes in to.
I've had two large crates from Spain arrive this summer, containing Barbary Sheep, Ibex and Boar.
They arrived via TNT. In fact every european trophy shipment I've had has been via a standard courier.
As far as I can tell whilst we are still in Europe there is no need to use a broker etc. Just book a standard courier to do it.