Allow Your Cat to Establish Boundaries Your older cat may hiss and swat at the kitten when the newcomer does something unfavorable. This is completely normal and as long as it is just hissing and swatting, do your best to not interfere. Your older cat is teaching the kitten where its boundaries as the new cat are.
Don't Allow Fights
While they may want to fight, don't allow your cat to do anything more than hiss and swat at the kitten. If you're concerned that a fight is about to happen, distract the cats with a loud clap of your hands or a quick squirt of water.
Again, some hissing when they see each other is normal so don't be alarmed. Some light swatting is also common. Separate them if the hissing doesn't die down after 1 or 2 minutes or if there is any sign of threat (swatting with force, chasing, screaming, ears flattened, etc.). Try again when the cats seem to be calm.
Cats are territorial creatures. As a result, your resident, older cat likely feels that an uninvited cat is invading their home. In most cases, the older cat thinks that they own your home and that a new kitten is a threat to that. Therefore, they can act out to assert dominance and stake claims on their territory.
It's common for kittens and young cats to engage in rough, active play because all feline play consists of mock aggression. Cats stalk, chase, sneak, pounce, swat, kick, scratch, ambush, attack and bite each other—all in good fun. If they're playing, it's reciprocal.
If your cats flatten their ears, hold their ears back, or puff up their fur or tails, this is a sign that they're fighting, not playing. Defensive, puffy postures and leaning away from each other while hissing with bared teeth are signs that your cats feel threatened and aren't having fun.
Playful, energetic cats may slap each other as in invitation to play. Cats that are inviting play by slapping will have body language fitting a playful cat. Their whiskers will be forward and their attention given to the situation at hand. Their claws will be retracted for the slap so as not to hurt the other cat.
Most of the time it just takes a few weeks to a month or two. I've had situations where the establish cat hissed at the new kitten until it was a year or two old, however. It depends on the personalities of the cats and their early upbringing. In most cases these things work themselves out fairly quickly.
Look for a cat who doesn't mind sleeping on the couch. Cats who are very playful and confident when they see other cats are more likely to get a long with a kitten or an energetic young adult. The new cat will keep them occupied and will be young enough to adopt the rule structure of the older cat.
5. Stay Patient Through the Introductions. Many cats can learn to live together, but it's up to you to give them time to get used to the idea. You should expect the introduction process to take no less than a week but could take much longer depending on your cats' temperaments.
If they're 'just playing', let them do their thing! If cats that normally play fight have a more 'aggressive episode', owners should never directly intervene – this may escalate the cat's anxiety and lead to increased aggression between the two cats or even towards the owner.
Don't be alarmed by hissing or growling. These are normal reactions. Encourage interaction through the door. Place your new cat's food near the door of his room so he stays near it.
Cats that have set up separate territories in the house and don't really get along will: Chase or run away from one another and avoid contact. You may notice that one cat consistently leaves the room when one enters. Watch each other intently and may hiss or spit when they meet.
Separate the kitten into its own area, which is completely cut off from your older cat, for example in a spare room. This may seem counter-productive to getting them more used to each other, but your older cat will need time to settle down and re-establish their comfort level in their own home.
Signs of aggression include dilated pupils, ears flattened backward on the head, tail held erect with hairs raised, and an arched back.
One of the best ways to help your cat grow up to be well-adjusted and anxiety-free is to ensure they're well socialized as a kitten. Expose your cat to a variety of social situations and experiences while they are young to decrease the likelihood of them developing anxiety in the future.
Single kitten syndrome is the idea that young kittens, when raised with other young kittens and cats and then adopted into a home by themselves, can become aggressive, anxious, stressed, and even develop behavioral issues like inappropriate chewing/scratching and inappropriately using the litterbox.
Introducing too quickly with little preparation will often lead to cats feeling threatened and scared, which increases the chance of aggressive behaviour being shown. Once cats feel this way about each other, it can be extremely difficult to change their minds.
Don't interfere in their interaction unless necessary—Some hissing and growling are normal and will stop as the older cat gets used to the kitten. Step in and separate the cats only when the situation escalates.
The short answer is yes, cats do experience separation anxiety. However, there's more to learn about the way cats process separation and the symptoms they may display if they have separation anxiety, too.
Make sure your cat is healthy
A big factor to consider is your cat's health. Apart from their mental health, their physical wellbeing is equally important. If your cat is unhealthy, a new kitten will stress them out and this will just aggravate the situation.
Rarely will the mom cat, big or small, take the next step of nipping or biting at her young and she is careful to not overly reprimand the very young kittens, yet becomes stronger in her discipline as they mature.
Cats that feel insecure may show different behaviors that can be interpreted as jealousy. Signs include aggression (such as hissing, swatting, growling, or even unprovoked attacks), and stress behavior (such as hiding, or peeing or pooping outside of the litter box).
Signs of Emotional Trauma in Cats and Dogs
Trauma can also manifest as “shaking, hiding, urination and/or defecation when the trigger attempts to interact, howling, pacing, excessive vocalization, and panting,” says Pia Silvani, director of behavioral rehabilitation at the ASPCA's Behavioral Rehabilitation Center.
If there's another cat in the home, it also gives them a chance to hone their social skills with members of their own species. It's common for kittens and young cats to engage in rough, active play because feline play can consist of mock aggression. Many cats retain this kitten-like behavior well into adulthood.