Help please🙏🥹

Hello, Vets! Can anyone please help? Male yorkie, 1.5 kg, 9 years old, not neutered, few years ago started having some kind of seizures (usually when sleeping on his stomach he wakes up gasping for air, falling down, the tongue turnes blue , we try to open his airways, from his mouth comes out yellow-green mucus ) Vets suspected liver shunt, but ruled out that, then his heart, but also says it’s healthy ,like his kidneys ,too.So now says could be collapsed trachea that causes inability to throw up…not so sure about that because he doesn’t even have the reverse sneezing…for about a year he was fine and recently started again.Can anyone suggest what to do and check next, or have the similar case to help us with diagnose what this is , because more than two years he doesn’t have the right diagnosis 😞( p.s.few years ago you helped my friend’s dog with diagnosis and she is now healthy happy girl , she recommended this group to me ,hoping you can repeat that miracle!❤️)

Hello - it sounds to me as though your vet is a ways through trying to diagnose this problem, and may be getting to a point where you are losing the faith.   Personally I wonder that the liver appears small on this radiograph, although without the original picture or much more context, I would not venture to give an opinion or second opinion on this site; I am not your vet and am in no position to be. I find that when a case reaches this point, a good question for your vet is 'what could it still be that you haven't ruled out?'   If they have no more likely differentials - or are unable to distinguish between them - then it may well be time to refer.