Many cats seem to prefer a solitary lifestyle, so if a new cat is added to the household, the fur may fly. Properly introducing a new addition can not only make the initial process a lot less stressful (for cats and people alike!), but also reduces the likelihood that problems like interanimal aggression, spraying, and stress-related behaviors will develop in the future.
Difficulties between cats are best prevented rather than being treated once they arise.
The best way to prevent problems from developing between cats is to take the introduction process slowly. Place the new animal in its own, separate room for several days. Allow the two cats to smell each other and interact through the door. Try to keep the first cat's routine as normal as possible. Once the animals have gotten used to the other's presence through the door, they can be allowed to see each other, but should still be physically separated. Screened doors or baby gates stacked one on top of the other are ideal for this purpose. This set-up should be maintained until the cats interact through the doorway in a friendly manner. If aggression does arise, go back to having a closed door in place until the animals are calm, and then try again.
At this point, the cats can be brought together for short periods of time. If they act aggressively, quickly intervene (an air horn or a blast of compressed air will often do the trick) and return the animals to their separate spaces. Once, the cats routinely tolerate each other during these "play" sessions, they can both be allowed to roam the house freely. Make sure that several feeding stations, litter boxes, perches, and hiding places are available so that the cats can avoid each other when they so desire.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008