How Do I Know When "Contagious Period" URI is Over???

Sorry about all of these questions but I'm a total newbie at this!!

When I got my cat from the Humane Society yesterday, they indicated that he had an upper respiratory infection but started meds (Clavamox) a week ago...they gave me a 2 week supply, 2 pills per day. The problem is, the cat doesn't *appear* sick. My friend said that his eyes seemed a little glassy but I can't tell. His eyes/nose are clear. The only indication I have is that when he purrs, he sounds a little congested. He's eating and drinking just fine and is active and playful.

I have him isolated from my other cat. Should I assume that he's "cured" after the 2 weeks of Clavamox? Maybe he's just a "rusty purr-er" and I wouldn't know whether he was still sick or not. Or do I need to take him to the vet in 2 weeks, just to be sure? And I've been reading that cats can be "carriers" of URI. Does that mean that he can be completely cured and still infect my other cat? I would appreciate any advice.

If it's a virus, he should be over it before the two weeks is up. And no longer contagious. As far as being a "carrier", they're just talking about the herpes virus, which remains latent in many cats. That doesn't mean they're walking sources of contagion. I'd just give the medication as prescribed and start introducing them in a week or so. Sure, your other cat might get the sneezes or the sniffles, but that's pretty much the routine with bringing in another cat. Not to worry, all will be well!!

The herpes virus that causes the URI symptoms, such as sneezing, crudy nose, weeping eyes and lack of appetite is like any other herpes virus.....it never goes away.
It is estimated that close to 95% of all domestic cats are infected. Stress is what usually brings on the symptoms and once the stressor is removed the problem clears up, although cats with weakened immune systems to begin with can have chronic flare-ups.
Unfortunately, cats actively showing signs are also actively shedding the virus. So any cat in close proximity will probably become infected.
In all likelyhood your existing cat is already a carrier...given the statistics.
Regular vaccinations will help prevent flare-ups, but the potential is always there since this problem is brought on by stress.
Your vet no doubt prescribed the clavamox to combat any secondary bacterial infections that might arise. Clavamox does virtually nothing to eliminate the virus.
On a positive note, it sounds as if what your kitten had, is clearing up and is most likely not actively shedding the virus at this point.

Also think about the antibiotics as if your own doctor prescribed them for you. They need to take the full 2 weeks to make sure and bacteria is gone. Several yrs ago I had rescued a barn kitten who amoung other things had herpes. It took my vet trial and error (and 6 months) to "cure" him. He was always a sneezy cat but luckily none of the others ever got ill.