My 18 year old cat died last month, my 15 year old cat, was very upset. We got a new kitten, from a shelter. Since the new kitten, the 15 year old, has done a great deal of hissing, sometimes to the point where he hisses so much he gags himself, now his meow is horse, and he is coughing a lot, as well as swallowing all the time. He is sleeping a great deal, and is not eating as much. He is not himself, changing where he sleeps, and does not 'talk' to me , as he was very vocal. He is getting along much better with the kitten, but they are not tight yet. The huge vet bill from the cat we had to put down due to kidney failure, has left us strapped financially. I am wondering if this will go away on its own, if he has a sore throat, or if it is more serious. Did the new kitten bring something into the house? Please any help would be so appriciated. I will take him to the vet, if we have to, but the last time I took him, for something I thought was serious, there was nothing wrong, and it was $253.00. All to tell me he was angry and was peeing on the floor because he was mad. Please... help?

Your 15 y/o cat has a lot on his plate. Not only has he lost his long-time cat companion, but now has had a lively kitten thrust upon him to disrupt his sleep and calm life.

Is there a way to separate the two cats and introduce them gradually (which should have been done in the first place)? The older cat needs some private time with you and peace during the day. The hierarchy has been totally upset.