Does anyone know what could possibly be the reason for pulmonary edema in a 12 year old Boston Terrier that does NOT have congestive heart failure? Heart tests came back normal, but xrays can not pinpoint a cause until the fluid is out. He suspects it is a problem with her lungs. Her breathing is not improving after vet suggested to double her daily amount of Lasix. Without proof of what's wrong, he refuses to speculate and I can't get an answer. Does anyone know any other factors that could cause this condition?