My 10 year old Chihuahua (male) has recently been diagnosed with an enlarged heart. When he went for his regular wellness check up the vet heard a murmur and suggested an x-ray which revealed an enlarged heart (not entirely huge, but larger than normal.) He has also coughed for several years and though I brought that up to the vet in the past, they told me small dogs often have a problem with a collapsing trachea. In any event, it appears that his cough is as a result of fluid in the heart chamber. I now have to take him to a cardiologist. I'm sure they will want to medicate him, which I'm not entirely in favor of, but I don't want the situation to progress either. Other than the coughing and apparent enlarged heart, he's spry and happy.