Legally if you arrive at the abattoir without loading gates, then the State Vet can condemn your pigs.
Unlikely to happen in practice, but I have heard of a beef animal being condemned this way. You'll be charged for slaughter, of course you'll not get your meat back and then be charged again for disposal of the meat
So maybe a small risk, but one nevertheless, so up to you !
Gavin, the rules are nowadays made up in Brussels by guys who have never even seen a pig !