Instructions
Keep the scared cat separate from other cats for about a week. The space the scared cat is in for the time being should be small, such as a bathroom, pantry or large cage. Provide the cat with fresh water, food, bedding, a litter box and toys.
Feed some of the other cats in the group on the opposite side of the door or cage where the scared cat is being kept while feeding the scared cat, as well. This associates the smells of the cats in the large group with something pleasant: meal time. If the cat is in a cage, cover the cage with a blanket so the cats cannot see each other and feed the other cats in an adjacent cage to prevent fighting through the bars.
Interact with the scared cat during the isolation period. Offer treats, play games with toys and spend some time just relaxing and petting the cat. This will put the cat more at ease and prevent overly fearful behavior.
Put the large group of cats in a separate room and let the scared cat wander their surroundings and get used to their smells. In the meantime, let the group of cats get used to the new cat's smells by giving them the new cat's bedding or putting them in the isolation room. The more familiar the cats are with each other, the less likely they will be to show aggression and fear.
Introduce the scared cat to cats in the large group one at a time. Do not put the scared cat in a room with more than one other cat at a time. Play with the cats during this introduction and offer treats for good behavior. There may be some hissing, but hopefully, the scared cat will have lost some tension during the isolation period. If you see signs of aggression, including growling, flattened ears or crouching, clap your hands to distract the cats. When the aggressive behavior stops, offer a treat.
Continue putting the scared cat around each cat in the group one a time for longer and longer periods of time. Once the new cat seems comfortable with each cat individually, try adding two or three in the room at a time. Watch for signs of aggression or signs of fear, such as backing up or hiding, in the new cat. Troubleshoot these issues as they arise.
Set up one more litter box than you have cats in the group. This will prevent any cats in the group from frightening the new cat while in the litter box.
Feed the cats at set times during the day and give each their own food dish. Free feeding can cause fights when the food is low, which can increase fear from the new cat. If the other cats in the group hassle the new cat once they finish eating, place them in a different room during feeding time.
Give the scared cat a special space in your home that can be used as a retreat. Set up the bedding you used in the isolation room in a private area. If the cat has bonded with you, then a space near your smells and where you frequently are, such as your bedroom, is a great place.
How to Care for a Scared Cat in a Large Group of Cats
If you have several cats or if you're introducing a cat to a shelter situation where it will await adoption, it will be more challenging to effectively care for a cat that is overly fearful. A scared cat is going to need more attention and socialization to become adoptable or to make a good pet. Providing this level of attention will be difficult if you have a large group of cats, but with the right commitment, you can give all the cats the care they need, including the scared cat.