You should mention age of your dog in your question. Breathing problems in dogs can be due to many reasons. Following is list of some common conditions that can disturb breathing in dogs.
1. Heart diseases
2. Heart failure
3. Heartworm
4. Lungs diseases
5. Fluid in lungs
6. Trauma
7. Tumors or cancer of lungs
8. Pneumonia
9. Bleeding in lungs
10. Obstruction of air passage
11. Pain
Loss of appetite is related with any illness in dogs. So, it will be good to take your dog to vet because treatment depends upon underlying cause.
1. Heart diseases
2. Heart failure
3. Heartworm
4. Lungs diseases
5. Fluid in lungs
6. Trauma
7. Tumors or cancer of lungs
8. Pneumonia
9. Bleeding in lungs
10. Obstruction of air passage
11. Pain
Loss of appetite is related with any illness in dogs. So, it will be good to take your dog to vet because treatment depends upon underlying cause.