Older cat stopped liking new kitty

Question
We have a 6 yr old male altered cat and we brought home a new female altered kitten 2.5 months ago that was 5 months old at the time.  Everything seemed to be going great.  The male did show he was boss, and the kitty cowered down to him.  They even play chased and "rolled" around a bit.  And I even witnessed him licking her belly, neck, and ears.  Just recently (last two weeks) the older cat has "rejected" the kitty and hisses, moans, and runs her off.  He even does it when we to us when we pick him up.  Although, he still sneaks into our bed everynight to snuggle.  But he disappears during the day and really has nothing to do with anyone and seems pretty irritated when we/kitty approach him. He used to play with our dog too, and now does not.  We just assumed that adding the kitty to our house was a success according to his behavior and now we don't understand the change in him.  Can you help?

Answer
Hi Sabina,

It does sound like everything went well with the new one. If the male has a change in attitude towards everyone in the house then I would take him to the vet to be checked out. He may be in pain from something and because of that doesn't have the patience with everyone around him. Any change in behavior towards the negative is something to be checked out. Good luck and let me know what the vet says.

Ciao, Karen