Last week Jack started to sneeze. Uh-oh. Kitty cold time. Jack had a URI (Upper Respiratory Infection). Cat colds aren't quite like the ones we get. Once a cat gets one of these and recovers, the virus goes dormant and can come back when the little kitty is stressed. Often the cat will get viral conjunctivitis (pink eye) along with it. Kittens have a harder time with URIs because their immune systems aren't quite fully developed. They could get a secondary bacterial infection. Because of this, cats are often put on antibiotics, but these of course cannot cure the viral URI.
Jack fortunately did not get the conjunctivitis. He was miserable for about two days. His nose was congested and he breathed through his mouth for several days. Jack did have a hearty appetite so no vet visit was necessary. His sneezing lasted about a week, and he is back to his normal self.
I kept quite a close eye on Jack while he had this cold. When Abigail was a year old, our new kitten Daisy passed on her URI to Abby. Abby became quite sick and stopped eating for 3 days, even while she was on antibiotics. She had to go to the vet several times for sub-q injections to rehydrate her. She also had a high fever.
Achoo! Uh-oh. URIs are very contagious. Baby started to sneeze a couple of days ago. She already sneezes once or twice a day from some unknown allergy, so at first I was not concerned. But her right eye started to squint and became watery. I put antibiotics in her eyes to combat any secondary infection. I also put extra water in her food to keep her well hydrated. She is already feeling better.
So far there is no sign of this cold in the other three, older cats. I may be lucky....