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Hello. Thanks for the question.
There are a couple things that could lead to rapid breathing. It could all be related to the congestion in the lung lobe. That could be pneumonia, heart disease or cancer. unfortunately, they can all look very similar and it can be tough to differentiate. I find body temperature to help a lot- it is usually low with heart disease, high with pneumonia or normal to high-normal with lung cancer. Normal is 100-102. You could take a rectal temperature with a digital thermometer to give you a better idea.
The anemia can also contribute to the breathing. The lower the red cell count, the less oxygen they are able to move around the body. They have to breath more quickly to make up for that anemia.
If the temp is < 100, then I would lean toward heart and get him rechecked. In that case, he would need to go on a diuretic to move the fluid. If it's > 103, then I would give it more time with the antibiotics. If it's 100-102, then I would think cancer or asthma and try another dose of Pred to see if it helps.
I hope this helps, let me know if you have any other questions.