Get to DVM or emergency immediately because ME dogs are very prone to AP and it can come on very suddenly.

Diagnose with 3 chest x-rays  (not just listening to the lungs which may sound clear but x-rays often lag behind the AP)
It is best to have 3 different views of the chest taken, when looking for aspiration pneumonia: one taken w/ the pet laying on it’s right side, one laying on it’s left, and one w/ the pet laying on his back, or on it’s stomach. We suggest 3 x-rays for the following reason: We can see things on an x-ray depends on the difference in density in air, tissue (or fluid), fat and bone. Pus and debris in the lung will show up as white, surrounded by black (air). However, with the dog on it’s side, if the pus (white) is located to the side of the heart, which is white also, that pus will just “blend in” w/ the heart and the pus won’t be recognized. So that’s why we also need an x-ray w/ the dog laying on it’s back, then we can see on either side of the heart. However, if we get an x-ray just on one side, the down lung is compressed, making it the same density as the pus and debris; when the dog is turned over, now the lung expands and fills w/ air, allowing the more dense pus to show up. So, we just have more of a chance of picking up subtle changes, or abnormalities that we would miss if we just take 2 x-rays. If finances are an issue, we just may have to do w/ 2 x-rays, but, 3 views is the best.