how long?

Hissing and spitting might indicate that your kitties are in pain and sick.

That is providing they don't react that way to you normally.

 

I would say that cats are normally very secretive when it comes to show that they are sick.  Most of the time they heal and you won't even know about them being sick.  But if they display anything strange - that's the time you worry.

I normally take mine to vet if anything out of ordinary happens.

 

If your kitties show any unusual behavior - I would advise you to take them to vets straight away.  They might be hurt or sick, they might not be, but why risk it?  They can be helped early instead of contracting something serious which will be difficult to deal with later.

 

We find it takes about 3 weeks for most cats who come into the shelter to catch the URI that we fight all the time, and show symptoms.  So, it's very possible your cats picked up this very common infection in the shelter. 

 

It's not much worse than a cold for humans, but if a cat is showing real distress, a visit to the vet is in order so that he can treat the secondary bacterial infections that might arise.  Antibiotics have no affect on the original virus that causes the original infection, however.

Stress and being in a shelter absolutely is the cause of this virus. If it is a virus, it is true that antibiotics won't help BUT most times with these cats it turns into a secondary bacterial infection and then antibiotics are needed. I would take the cats to your vet for a check-up and most likely the vet might prescribe antibiotics. You could also start them on Lysine - which is in powder form and easily mixed in with the wet food. There are a couple of thread going on right now in the Health Forum on Lysine. They are under a great deal of stress and it will take some time for them to relax, settle down and realize that they are finally in a loving home and can trust you.

This is fairly common in "catteries" as my vet calls them.  All of mine had some sort of viral infection after I got them home.  Someone indicated stress as a factor and that is correct according to my vet. The hissing is most likely the cats expressing pain of some sort.  I think probably an antibiotic will help.  You might want to ask your vet about it and see what he/she suggests.  So happy you adopted those two kitties.  You are a good person

The stress of the changing environment probably gave them a flare up. Even if it's a positive move to go into a home, it's still stressful to a cat.

You def need to have them both looked at by a vet. If there is colour to their nasal discharge, green or yellow, it indicates a bacterial infection.

Same with the eyes. You can pick up some Lysine capsules at your health food store and give them some mixed with wet food. It will help build

up their immunity. Hope they feel better soon!!