Can purring affect breathing?

[tagv12]

Our Siamese (Chuck) who's 16 has been relatively
problem free until his lymphosarcoma 5 years ago but we have it under
control with Lukeran. Being the Siamese that he is he has always
been VERY vocal, and purrs everytime we are even near him. We noticed
about a week ago that his purr had changed and sometimes it sounds
like he's wheezing and other times his exhale is very long and it
sounds like he's slightly groaning on his exhale. I hope I'm
describing this clearly enough because it's very hard to put into
words. He went to the vet last week for a chest x-ray and check-up
and everything seemed normal. He's eating well, drinking etc, nothing else about him has change. The vet said maybe he has a throat
infection but his throat looked good, but did not do a throat culture
and sent us home with Clavamox. Now, some days he does sound better
(like yesterday), but today when we go and visit him in his bed and
starts to purr, his exhales are long and almost wheeze-like. Has
anyone ever heard of such a thing? It's almost like his purring
affects his breathing. If anyone has any thoughts please let me
know. I'm waiting for a call from the vet today to give him an
update, we are just so puzzled.

Thank you