asthma treatment

Hi!
I have a 3-4 year old Tabby. He has severe asthma, sometimes to the point where he's on the floor panting. I'm currently giving him some medication, I have been for about a year now. It's not the best, but I do see improvements. Anyways, I was wandering if there's maybe any herbal alternatives to treat his condition. Any help is appreciated.
Thanks
~Thomas

Thanks for the advide
I live in British Columbia, I can check around for some holistic
vets. But is there, say, any vitamins that might help him, even a little?
Thanks again.

my Linxy has asthma and is getting a prednizone(?) shot about every2 1/2 months. when he has an attack and I can't get him to the vet for the shot like at night I use a vaporizer in the bath it is the smallest room, to clear him up seems to help at the moment but by the am he'll have another attack and i take him in to get his shot. I am dusting & vaccuming more often and have got an air purifier and the last shot lasted him thru 3 months. It is so sad to watch him go thru this. If you find something that helps please share I also don't like that he will be on steroids all his life. Hugs to you and your furry!