Lethargic (and eye infection/gagging) cat after kitten introduction

Question
Here's the background:

My girlfriend has had a cat who knows me very well for the past 2 years.  He is about 2.5 years old, very very playful, and very excited to play with me whenever I was over.

Recently we got a kitten together, about 4 weeks ago, he's a 3 month old male.  The kitten moved into my place, about 5 days later her cat moved in as well.  Over the next 3 weeks (until now) my girlfriend moved all of her stuff in.

The kitten had an eye infection before we adopted him, but it had been cured.

After about 24 hours, the cat and kitten began to play, and for the next week chased each other back and forth all over the house, cleaned each other, and slept together.

Then the cat's eye got all puffy and infected looking, we figured that the cat had gotten scratched by the kitten.  Brought him to the emergency vet, and they couldn't see anything, so we got prescribed some ointment to put in his eye.

We've been administering the ointment for almost 2 weeks and the eye looks much better.  However the cat no longer responds to us, hasn't meowed in weeks (was very very vocal) doesn't greet us at the door, and if we try to pet him, he gets up slowly without looking at us and walks away.  He also doesn't respond to his name, or seem to care at all that we are around.  He is very lethargic, and seems almost determined to ignore us as much as possible.. he still cleans the kitten and allows him to snuggle with him.  The other weird thing, which we had checked by the vet, is that he seems to gag sometimes, we thought he had something in his throat, the vet said no.

Similarily if we do pay attention to him (which we're trying to do as much as possible) the kitten interferes immediately.  Basically anything the cat does, the kitten gets in the way as quickly as it can.. ie: cat sits on a chair, kitten will get up from sleeping, to go push the cat off the chair.

We're not sure what to do, we want our Cat to be happy and back to his usual self, is this just an adjustment period?  is he extra made because we're "torturing" him with eye drops?  He's also probably lost about 2 lbs, which isn't all bad, unless he keeps losing it.

Our vet doesn't seem to think there's a problem.

additional info:

they have seperate food dishes, with high quality cat food, seperate litter boxes.  Our home is 2 floors, with no doors (except the washrooms) so there's really no where to segregate them in a humane fashion.


thanks for your help!

Answer
Brian,

I'm very concerned about the potential for a fairly serious medical issue happening with your older cat, possibly due to some contagious viral/bacterial infection brought home by his new sibling. I'm guessing that you didn't isolate the new kitten in a room of his/her own for the first 2-3 weeks you had him. I normally recommend this because it serves as a brief quarantine period as well as allowing you to get to know your new friend and what's normal for them in terms of appetite, behavior, quirks, etc. The fact that the kitten seems to want to crave attention is absolutely normal - the fact that your older cat doesn't have anything to say about it isn't, especially since I get the impression that he was an energetic and spunky little guy before his new sibling came into the picture. I'm very concerned about the possibility that something serious is going on with your older cat's health - sudden behavioral changes, the red puffy eye (which may have been a simple case of pink eye or something more serious), the lethargy and significant weight loss (2 lbs is like 20+ lbs in a person of average weight) all point towards something concerning. Unfortunately by the time that cats are showing signs of illness they're often sicker than they look because it's instinctive for them to hide any sign of illness as a way of protecting themselves against predators. I really don't think that changes this drastic are due to the quick introduction of the new kitten or the eye ointment, I suspect that something more serious is going on and if your vet is dismissing your concerns get a second opinion. I think that a full pre-anesthetic blood profile and a full body x-ray will give the vet a more complete picture of what's going on. The blood work will allow a vet to know how the cat's major organs are functioning as well as if there is any sign of infection. The x-ray can reveal things like foreign bodies if they are made of metal or something else that shows up on the film, they also allow the vets a vague view of how large the heart is, if the bowels are enlarged or full of gas which might suggest something as simple as constipation or a potential medical emergency like a blocked intestine due to a really large hair ball or a foreign body stuck in the stomach or intestinal tract. A thorough physical exam will also allow the vet to listen to your cat's heart and lungs to determine whether there is any kind of defect or problem there, a good physical will also give the vet information like whether or not the cat has a fever or seems to be sore anywhere. A new cat being introduced to the household doesn't explain the drastic change in this cat - you describe him as quite active, outgoing, playful and vocal prior to this illness starting, he's still this cat inside, it's now a matter of finding out why he isn't acting like himself. I really suspect that something is happening medically and it may be quite significant which means that your cat should be taken to a second vet, examined thoroughly, diagnosed and treated as soon as possible - I would recommend that he sees a vet within the next 24-36 hours. It's quite possible that your cat will need to be hospitalized for observation if the vet can't tell for sure what's happening so it's best to prepare yourself for that possibility. I'm quite concerned that your new kitten has brought along a contagious house warming present for your older cat, but I really hope that I'm wrong. Just remember, you know your cat best, if you suspect that something's wrong (and judging by the symptoms there's something quite wrong) don't allow a vet to brush you off because odds are that there's a medical issue of some sort which would account for the sudden changes in your older cat.