It was a tumor.

The vet called… they found a tumor in Rio’s throat… that was a size of a fist. They removed it, but he said that this kind of tumor can happen with blue-tongued dogs and it is usually really aggressive. We are leaving now to go talk to him, but he said at least for now she is much more comfortable and breathing well again. He did say to Bryan that this would be definitely the thing that she ends up passing away from.