Thanks for the reply!
He has strictly upper respiratory problems, so I'm not sure an inhaler would be useful. Definitely no vet has recommended that to us over the years.
As for the rest of those factors, yeah, I mean I'm pretty familiar with the general mechanisms of allergies. In his case...
My soon-to-be 13 year old kitty Mushu has had intermittent upper respiratory issues since we adopted him at age 7. His previous owner indicated these have been an issue most of his life. It usually starts out with occasional sneezing, then turning into major congestion, constant sneezing &...