Whoever coined the phrase “fighting like cats and dogs” has never seen the level of conflict that can occur when a new cat is introduced to a house with a resident cat. The good news is that with planning and patience these introductions can go smoothly!
Before the Introduction (Planning)
Preparing the Cats
Before the cats meet each other, the new cat should be examined by a veterinarian, tested for infectious diseases (in particular, FeLV and FIV), dewormed, vaccinated and given a clean bill of health. If possible, the new cat should also be spayed or neutered, since spaying/neutering cats has both health and behavioral benefits (neutered cats are less likely to mark, and altered cats tend to get along better than ones that have not been altered). If the resident cat has not been tested for FeLV and FIV, does not have updated vaccinations, or is not spayed or neutered, this should also be done before a new cat is introduced to the household. Taking care of these health concerns in advance not only reduces the chance that one cat will spread disease to the other and helps make the initial introductions more harmonious, but also ensures the initial introduction process won’t be interrupted by one of the cats making a trip to the veterinarian.
Preparing Your Home
Before bringing a new cat to your home, you should prepare your home by setting up a separate room for the new cat. The new cat’s temporary room should have a door to provide separation from the resident cat. In the room, set up food and water dishes, a litter box, toys, and a comfortable resting place for the new cat. Place a clean towel over the resting place for the new cat and place a clean towel in another part of the house where the resident cat will likely rest. After the introduction is complete and the cats are freely and comfortably interacting with each other, the temporary room can have the door open at all times and you can slowly move the food and water dishes and the litter box to a more desirable place. Keep in mind that to prevent litter box problems that might occur if one of the cat’s access to the litter box is blocked, it is best to have one more litter box than there are cats in the household, and to have them located in different places and different levels in the house.
The Introduction (Patience)
Since cats are territorial, they should be introduced to each other slowly, with plenty of time to get used to each other before meeting face-to-face. Cat introductions should involve both desensitization (in which the cats get used to the smell, sight, and presence of one another before meeting) and counter-conditioning (in which the cats associate the other’s presence with something positive). A pheromone plug-in like the FELIWAY Multicat diffuser which uses the cat-appeasing pheromone can be used to help facilitate the introductions.
For a step-by-step guide to the introduction, see
“Introducing a New Cat or Kitten to the Resident Cat in Your Home: Part 2”
After the Introduction
After the introductory period, continue to monitor the cats for fearful or aggressive behavior. If the behavior intensifies, you may need to separate the cats and follow the steps to reintroduce them again. Since cats rely heavily on their sense of smell, it is not uncommon for cats who have been living together harmoniously to growl or hiss at each other after one leaves the house for a short period of time. To prevent this from occurring after one of the cats goes to the veterinarian’s office (or somewhere else) without the other, when you bring the cat back home, place its carrier in a safe place with a litter box and food and water readily accessible. Open the door to the carrier and allow the cat to slowly explore the surroundings. Use towels again to help exchange scents between the cats—the towel used in the carrier for the journey can be rubbed on the cat who stayed home and a towel or bedding used by the cat who stayed home can be rubbed on the cat who left the house. Again, expect the cat who stayed at home to hiss at the other cat, until he/she no longer smells like a strange place. After a short, supervised re-introduction period (hours instead of days) the cats should be back to interacting normally again!