What cat flu is
Cat flu is the everyday name for an upper respiratory infection, most often caused by feline herpesvirus (FHV-1) or feline calicivirus. It has nothing to do with human flu and cannot be caught from people. The typical picture is a cat with sneezing, runny or gummy eyes, a blocked nose, and sometimes small ulcers in the mouth that make eating uncomfortable. Some cats also seem tired or lose their appetite for a few days. Kittens, older cats, and cats with weaker immune systems tend to feel it the most.
Why it spreads so easily
Cat flu is very contagious between cats and travels through sneezes, shared bowls, bedding, and even hands or clothing. In homes and shelters where cats live close together, one sneezing cat can quickly pass it to others. Because of this, keeping a sick cat gently separated and washing your hands between cats can make a real difference. The viruses do not spread to humans or dogs, so you only need to think about protecting your other cats. Good ventilation and clean shared items help slow it down.
The herpes carrier for life
One thing that surprises many owners is that a cat who has had feline herpesvirus usually carries it quietly for the rest of its life. Most of the time the virus stays dormant and causes no trouble at all. During periods of stress, such as a house move, a new pet, or another illness, the virus can flare up again and bring back sneezing or watery eyes. These flare-ups are normal for carrier cats and are usually milder than the first infection. Reducing stress and keeping routines steady can help keep flare-ups to a minimum.
Care and when to see a vet
Most cases of cat flu are managed with supportive care at home, much like nursing a cold. Keeping the eyes and nose gently wiped clean, offering warm and smelly food to tempt the appetite, and making sure your cat keeps drinking all help a lot. You should contact your vet if your cat stops eating, becomes very lethargic, struggles to breathe, or if symptoms drag on or keep worsening. Kittens and older cats can go downhill faster, so err on the side of an early call. Your vet can advise on medication and check for any complications.