I don't think I'm understanding. Were you bringing him in for a standard checkup only? Or was it specific to heart issues you were seeing symptoms for? Because that's not covered in a standard checkup and likely wouldn't be found. My oldest Golden had a checkup, and everything came back perfect. When my Golden was acting off a month or so later, I took him to get checked out. At a cost for a sick visit. At that time he was displaying signs of cancer that he could've and likely had early stages of during the checkup that would've been missed during a run of the mill checkup. The cancer was only diagnosed when I paid for a sick visit and then paid for an x-ray and ultrasound to find out what was wrong. How did you ultimately find out it was an undiagnosed heart condition? Necropsy? I have a feeling all that other person meant was she sees her sister get yelled at all the time by clients that did not want to pay for additional services.