Fear of unfamiliar cats can be a normal and adaptive behavior, but can lead to more serious problems. Always take it seriously. Some fearful cats can show aggression and it can lead to serious fights between the cats, potentially leading to serious injury. Other signs of fear are more subtle, and you may not immediately notice it happening. Fear can result in stress signs such as not eating, not using the litter box appropriately, hiding or over grooming. If you notice these signs in one cat, fear of the other cats may be the serious stressor.
Even mild forms of fear, when not properly addressed, can evolve into more serious anxiety related problems. This is why it is important to address any change in your cat’s behavior right away. Work with a professional who can look at the context in which fear occurs. Never use punishment as a training technique as it does not work and only hurts your relationship with your cat. Fear related behavior towards any unfamiliar cats can occur in cats of any breed, size, age, or sex.
Pay attention to your cat’s body language. Signs of stress and fear are dilated pupils, ears turning back, a twitching tail, growling, hissing, swatting, and biting. You may also see increased fearful behavior such as a low body posture with tail wrapped around body. A fearful cat may exhibit an increased startle response and be more prone to running and hiding.
Always separate the fearful cat from the others to prevent worsening of the problem. If the unfamiliar cat is an outdoor cat, then windows should be blocked so that your indoor cat cannot see out. Another option for keeping outdoor cats away is using motion-activated sprinklers. For more information, read ‘How can I keep cats out of my yard?’ and ‘Reducing outdoor stress for indoor cats’
Don’t rush an introduction. If you are introducing an unfamiliar cat as a new pet in the family, keep the new cat and resident cat(s) separate at first. You are working towards a positive long-term relationship and being patient will pay off! Most cats will adjust to living within a multi-cat household.