Three weeks ago we adopted a 5 month old kitten to join our 2 other cats (17 year old girl, 19 year old boy). We took the introduction very slowly, he just started having access to the house a week ago when we are home and he sleeps in a closed room at night. Our girl cat is tolerating him, even letting him sleep next to her. Every now and then she smacks him in the head when he pounces on her, but overall it is trending well. Our male cat is the complete opposite. He sleeps all day in a chair in the living room (was active prior to the kitten) and hisses whenever the kitten comes near him. Last night he became very ill (dry heaving, soiling himself) and was taken to the vet. We are bringing him home tomorrow and I want to make sure he will be ok, but feel the kitten is a stressor for him. He just isn't himself any more and unhappy. I try to spend time with him, but he sleeps all the time now. It's breaking my heart. Also he won't eat or drink. I've brought his food to him on the chair, but it doesn't help.
Advice?
Advice?