My 6 year old red heeler (Rudy) has started coughing on occassion. He's been doing it for over a month now. I thought maybe it was kennel cough so I took him to the vet. He went on an antibiotic and that did nothing. So my vet prescribed another antibiotic and a cough suppresant for another week and still nothing. Then she asked me to not run or walk him for a week (I run both my dogs religiously once a day 2 miles) to see if he just needed time for his lungs to heal and that did nothing. Then on the 4th week, she put him on an broad spectrum antibiotic and that still didn't help. This week (into week 5now) she put him on something to open up his airways in case he has obstruction or a tight airway and it's not helping. Also, we ran a heartworm test and took x-rays of his heart. She said both looked okay.
The strange thing is it is not a continuous cough. He only does it when he seems to be going from a resting state to getting up and moving around. He'll cough when he comes running when I call him to come in the house but then when we go for our run, he either won't do it at all the whole time or maybe once.
I have noticed that he seems to be drinking more water as well.
I've looked up his symptoms and come up with a whole list of things from cancer, to lung tumors, to heart failure. I have a feeling that this is much more serious than I originally thought but I'd love to hear any other opinions.
Thank you,
Audrey

Yes, she did give him a heartworm test (at my request).
I worked for this vet for 3 years (years ago) but I do feel that if something isn't resolved soon, I may need to go to someone who has more advanced technology and is a little more dedicated to resolving the problem.
Thank you for the reply!!!