This may be a wild guess, but this sounds like the OP is a young, and un-eduated person. One that is only concerned with size, and not quality or temperament.
He/she is impressed by the VERY thought of a large Rott. So much, that they IGNORE the potential health risks, and financial responsibility of owning an animal that is not the norm.
At two pages and no reply from the OP I say we end this thread now.
Collars for yorkies to clydesdales are available online or in your own town, and this poster doesn't have a dog to fit one yet, nor did he/she post this looking for collars.
Just a response (which was given).
Hopefully some knowledge will leak through and we won't see posts later asking for help or health advice because his dog is ABNORMAL.
But, should probs arise of course, please DO ask. The dogs come first. No matter how BIG they are.
Ailee