Some links that might help. First deals with sneezing/ bloody snot. (for lack of a better word) 2nd is a chart of antibiotics and how to use them in rats. 3rd is a source for Tylan. Or, you might want to go ahead and take the rats to the vet since you're planning on using them as breeding stock.

Good luck getting your rat colony healthy!

http://www.rmca.org/Articles/respir.htm

http://www.rmca.org/Articles/dchart.htm

http://www.google.com/products/catal...d=0CFkQ8wIwAg#