Why is my dog with pneumonia and collapsed trachea coughing when eating?

Hello and thank you for reaching out to Petco Pet Education Center, formerly Petcoach. I'm sorry to hear that Cassie was diagnosed with aspiration pneumonia, but I'm glad to hear that she is getting treated with antibiotics. Your idea of trying to feed small amounts at a time may help her, especially if you can try to form the food into little meatballs (if it is wet food). If she normally eats dry food, you can moisten the dry food and form it into little meatball-shaped pieces. This make be easier for her to swallow and cause her to cough less afterwards. That being said, coughing is not a bad thing when dogs have aspiration pneumonia. Coughing means their body is trying to cough up the mucus and phlegm that is down in their airways, and bring it up and out so they can breathe better. Her historical collapsing trachea should not make it difficult for her to swallow fluids, although it may contribute to her coughing. As long as Cassie still has a good appetite, is drinking, and is able to keep fluids and food down (ie not vomiting), she may just require more time to get back to normal. Antibiotics can take several days before we see a clinical response. If she does not improve or you are ever concerned about her coughing or breathing, I recommend having her seen by your veterinarian, as a different therapy may be needed. I hope this is helpful - wishing you the best with Cassie!