Several weeks ago, my 14-year-old lab/chow mix, Wally, began making loud coughing/choking noises every half hour or so, for no readily apparent reason. The second day of his doing this, we took him in to the vet, and -- after x-rays and ultrasound -- he was diagnosed with DCM (dilated cardiomyopathy). What this means is that Wally's heart had enlarged to the point where it now presses (with increasing frequency) against his esophagus, making it steadily more difficult for him to breathe. (Hence, the bouts of choking/coughing). The vet prescribed various medicines for Wally -- Tussigon (cough suppressant); Furosemide (diuretic);...