Cool, Did some research on tylosin, and just like you said, it's an old school drug in reptiles that still works well.
One thing - recommended dosage in reptiles goes anywhere from 5mg/kg up to 25 mg/kg (IM). This is a discrepancy of 500%!! All these sources I'm talking about look legit.
This is just stuff I have found on the net, so I guess you have to use your own experience/judgement.
http://zcog.org/zcog%20frames/Reptil...ug%20Doses.htm
http://www.fauvet.fau.edu/oacm/VetDa...Data/snake.htm
Ritchie