I adopted brownie 3 1/2 years ago and at his first visit to his vet was informed he had a pretty significant heart murmur. He seemed fine and was doing very well until about 2 months ago when he started panting some at night . The vet put him on 2.5 mg of vetmedin in the am and half of 1.25 mg at night . His panting seemed to get worse at night only and the vet did an xray. He informed me that his heart was slightly enlarged and added the lasix. He never mentioned CHF. The panting continued at night and vetmedin increased to 1.25 at night causing severe panting and increased heart rate . His heart was also pounding very hard . I immediately stopped this and vet changel him to half 5mg of enalapril twice daily. The first dose was that night and it also caused extreme panting and increased heart rate. His heart also pounded very hard. I kept him on the lasix and he does well during the day but pants with the increased and irratic heart beat starting about 7 each night . No other test have been performed . This is a small town vet and I would need to go else where for the testing outside of blood work. I don't mind doing this if it would help. His heart rate now is 92 beats per minute . My sis in law is a RT and came to listen for me . I did not know if vetmedin could be lowered . My vet office closes at times for him to take care of large animals and I can't always reach him. He is still very active and loves to chase his ball inside . I do think the diuretic has helped . His panting is more smooth if that makes sense and it's odd that he has stopped most urinating accidents or marking in the house since on it. No clue why . He sleeps with me and would get up during the night and urinate in the same places most nights . Maybe three times now in last month . I have never heard him cough at all .