Originally Posted by
Caretaker
Definitions:
Irish railways have always 'defined' bicycles as 'dogs' and even in the day of touchscreen displays still issue a ticket to cover both.
My touring bicycle has occasionally bitten me on the calf but as yet all my attempts to enter it in dog shows have been rebuffed.
Odd, I don't see that anywhere on their site:
Bicycle Information 
I don't doubt that they may offer a supplement ticket that covers both (and probably other things like luggage as well, if it is like any of the other Euro trains I have been on), but I don't see how that logically jumps to meaning bikes are defined as dogs.