Why Do Cats Hiss at New Kittens or Cats?

A cat considers your home its domain, so when you introduce a new cat or kitten, that threatens your existing cat's territory. Because of the smell of an unfamiliar animal, the cat will hiss at the new feline to establish its dominance over the territory of the home. After this initial period of introduction passes, your cat will acclimate itself to the new member of your household.

  1. Hissing

    • A cat hisses as an act of aggression toward another cat. When it hisses, a cat mimics a snake, an animal that most mammals are afraid of. The cat opens its mouth, draws back its lips and wrinkles its face before expelling a strong gust of air to make a hiss. The cat may even spit when it expels the air. Because a cat considers a new cat of any age a threat, it hisses at it to scare it away. Hissing is meant to prevent a possible attack from the new, unfamiliar cat, rather than to instigate one in most cases.

    Authority and Resources

    • An older cat will hiss at a new kitten to send it a message that the kitten should respect the older animal's authority in the home, says Petplace.com. A lack of proper resources for the cats can add to the feeling of animosity between the animals, because the existing cat views the new cat as competition for these resources. The American Society for the Prevention of Cruelty to Animals recommends that you provide your cats with climbing trees for them to escape to, and separate food and water dishes and litter boxes in different parts of your home.

    Sexual Behavior

    • A non-neutered male cat, also referred to as "intact" because it has not had its reproductive organs removed, will hiss at another male cat due to the sexual hormones in its system, says the Hilltop Animal Hospital. The existing cat views the new cat as competition for a potential mate, especially during the breeding season in the warmer months of the year. Hissing and posturing can lead to a physical altercation between intact male cats, especially during introductions. To prevent this type of behavior, have the cats neutered before allowing them to meet each other.

    Introductions

    • To reduce your cat's anxiety and hissing at the introduction of a new cat into your home, take the initial introductions slowly. Confine the cats to separate parts of your home. Wipe each cat's cheeks with a towel, and allow the existing cat to smell the scent of the new cat over a period of a few days -- and vice versa. Feed the cats on opposite sides of a door for another few days so that they associate food, a positive experience, with the presence of the other cat. Use a pheromone spray to calm both animals during the meeting and during their first few weeks of cohabitation, recommends the ASPCA.