POOR BABY ! I'm so sorry to hear this....at 13 that may be a problem if surgery is a consideration - but they CAN operate in some cases - I know some people that have had sucessful operations but they were on younger yorkies and it all depends on where the bad parts are located I think....I sure have no advise but to read ALL you can -
I did find these sites - there is some good information here - one applies to Maltese but they are very similar to yorkies in structure and size -
http://www.petsurgery.com/surgicaldiseasesofairway.html http://www.malteseonly.com/trachea.html
and THIS is a help site set up by Yorkie Rescue -
http://www.yorkierescue.com/trachea/tracheaapp.html
It must break your heart seeing her not be able to breath - I would suggest you try to find a vet that will be honest and forthright and tell you if she is really suffering.... or if she can be helped - you don't want her in pain.....Bless her heart - GOOD LUCK TO YOU !!!