Vet has said that some owners use Glucosamine Condrition for their dogs with collapsed trachea?

I have a 9 year old Lho/Poo. been noticing a cough and like he wants to vomit. Vet thinks its a colapsing trachea. Said some other owners use Glocosimine Condrition supplement because its made from the trachea of cows (that weirded me out!) but she saw no clinical evidence. any suggestions? I want to help my little pup as much as possible, whatever I can do to prevent it from getting ay worse.