Proving there is no rule about importing animal parts into Spain, I don`t see why not. There are a whole lot of rules/laws about carriage of dangerous goods and antlers aren`t dangerous goods.
I wouldn`t put them in a case. The loaders will chuck other cases on top and they`ll get smashed to bits. I`d wrap them in thick bubble wrap and put fragile stickers all over them.
Fragile or not, the loaders will still chuck them about. I remember seeing a lot of boxes coming out of a hold with "Fragile, live fish" on them and they were being chucked about all over the place.
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