One of my cat was vomiting so I took him to the vet. Turns out he is fine, just some sensitive stomach or whatever. But now the other cat doesn't recognize him any more. She has been hissing at him for three days now. Are they stupid or what? Will this last for another week like the first time they met?
The cat is probably reacting to the smell of the vet on the cat that was sick. They'll get back to normal soon, probably sooner than it took them to get used to each other the first time around.
Actually, it isn't stupidity, it's protection. A cat's nose, while not as sensitive as a dog's, is still 15-20 times more sensitive than a human's nose. When a cat smells other animals, a foreign environment, etc., they hiss as a show of strength and as a just-in-case warning. For them, another animal walking in smelling like they were covered in fifty dogs and cats would be like you walking in to the bedroom smelling of woman's perfume with lipstick on your collar and face. My guess is your wife would do more than hiss.
