I'm sorry to hear that your Min Pin is going through this. There are several things that may be causing his symptoms. It woud be in his best interest to have an echo run again, but, you may also want to discuss with your vet if his symptoms could be the result of one of the following:
Laryngeal Paresis: http://www.petplace.com/dogs/laryngeal-paresis-and-paralysis/page1.aspx
Tracheal Collapse: http://www.petplace.com/dogs/tracheal-collapse-collapsing-trachea/page1.aspx
Palate Disorder: http://www.petplace.com/dogs/soft-palate-disorders-in-dogs/page1.aspx
I hope he's doing better soon and if you need any other information, let me know. -Robyn
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