New lasix prescription question

Hi all - my 10.5 year old girl has had quite a mitral valve murmur (grade 6) for some time. Shes been on vetmedin and enalapril for 4-5 years. Lungs have thankfully been clear the past recent visits (<1 month ago). Over the past week, breathing became more labored with more frequent coughing.

Vet today said she heard a small amount of fluid in the lungs and recommend we go ahead and start Lasix, we’ve got an upcoming cardiology appointment. She was given an IM dose today and a prescription for 12.5 BID. We didn’t do labs or anything, no xray.

Are those things routinely done before starting Lasix? She did have routine labs 10/6. Does 12.5 sound like a lot for a 10 pound dog?

I used to work in emergency medicine for humans so I know animals can be a little different with these things. Thanks all!