Thank you all for your replies.

I spoke with Sheryl tonight and she said that Tux is still coughing a bit, not like he was at the beginning of the week and is breathing easier. He is taking his pills very well. He is still eating & drinking well and was even chasing his brother at one point. But she did say that he seems to be sleeping more than usual.

Maya & Inka's mommy; No you didn't scare me at all and we do know the seriousness of his condition. The vet told my sister that Tux could have a heart attack, it's just a question of when..