behavioral problems

Question
hello!  i own 2 cats a 6 year old male tabby and a 6 month old female tiger.  They adapted to eachother fairly quickly and became friends (cleaning each other and sleeping together) within a week of getting the kitten.  the female just went in to be spayed a couple weeks ago, she was gone out of the house for 3 days. during that time the older male cat became very affectionate with us which i assumed was only because he missed his friend and had no one to keep him company. when we brought the kitten home the male's attitude did a total 180. he hissed  and attacked her like she was a new cat and had one accident the kitten was still not up to full recovery so she just laid down and took it.  we thought everything was getting better, they were running around with eachother and cleaning eachother. then a few days ago, which the beginning of summer heat we set up the a/c in our apartment and he's been hiding ever since, but still comes out to play, eat, drink and  use the litter box.  but whenever we approach him and pet him (more then one or 2 strokes) he gets angry and hisses and snaps at us. this is definately not his normal behavior. we tried turning off the a/c and he still hid and only came out late at night like previously. he is usually a very loving cat especially with me and it's very odd for him to hiss at me.  i know he's been under  a lot of stress this past year 2 moves an incident with fleas and a new kitten, he did have some stomach issues as well but that was cleared up by our vet.  i'm just looking for some advice b/c i miss my old cat and i definately don't like this new aggressive one. thanks!

Answer
Hi Jessica,
You didn't say, but has he been neutered? If not, then some of the aggression may be a result from that, but I really think the main thing that set him off was when your kitten came home from being spayed she "smelled" different.  While at the Vet clinic, she took on the different odors from there and when he smelled all of that, he didn't remember her as his old buddy, but as a type of rival.  I have seen this time and time again.  It is usually the male that behaves so badly.  Good news though, after awhile he will go back to being his old self. The thing is, cats HATE change.  With her being gone and coming back "smelling" different, the two moves you mentioned, the fleas that you probably treated with more "smelly stuff" and then there's the A/C that probably makes strange noises to him.  Honestly, some cats do better than others with change but none like it.  Give him some time, I really think he will be fine.  Be sure and have him neutered though, if he isn't, because he will continue to be agressive to your female if you don't.

God Bless,
Becky