I have a 9 year old dog. We rescued him when he was 8 months and are unsure of his breed. He was 85lbs at his heaviest. Now he is down to 71lbs. Starting about a week ago he stopped eating. We were been able to get him to eat turkey and ground beef for a couple days but he even stopped eating that for us now. All I can get him to do now is lick a little peanut butter. About 3 days ago his breathing has become labored and he whines or groans with each exhale. He has been to the vet 3 times. The first time they did complete bloodwork. According to the Vet his blood work was perfect. Nothing was out of the ordinary. She also did a full array of xrays and was unable to find anything that could be causing this. We were sent home with pain medication and anti-nausea medicine. After a couple days there was no improvement and he still will not eat. He had more xrays done and was checked by another vet who stated that he thinks there is a mass but was unable to tell where he was feeling it. We had an ultrasound done today and the tech said she could not see any masses or foreign objects and everything appears normal. We are waiting for the official word from the doctor though. They have checked for heartworm and ticks all negative. No issues with the heart or lungs. I just hate to see my guy in pain and he is getting weaker due to not eating. He is still drinking and peeing. Any advice anyone could give will be greatly appreciated.