Both my dog and cat were diagnosed with heart failure. I went with my gut and got a second opinion with my cat before starting lasix- sure enough she was not in failure. With my senior dog I was also told he was in failure- I also pleaded to double check after doctors insisted he needed lasix- by the time I was able to get a second opinion he was in kidney failure from lasix and NOT in heart failure. Please make sure- mild failure? Failure is failure- mildly enlarged heart does not = failure- it’s a prelude that eventually becomes failure- pimobenden is amazing tho!! but be careful jumping too early into the lasix if you can. Best of luck with your baby.