Introducing Cats

Desensitization and counter-conditioning are the keys to introducing cats.  The first phase involves desensitizing the individual cats to each other.  Once that is accomplished, the cats are then counter-conditioned to view each other in a positive manner.  The entire process of introduction may take weeks to months.  As with all things related to animals, patience is required.  Cats move at their own pace, not ours. 
In my experience, cats of the same sex get along better then opposite sex pairs.  Make sure both cats are healthy and free of disease before introducing them.  Quarantine new additions for at least two weeks before starting phase one!   


Set up a safe room for the new cat with their own bowls, bed and litter box.  Give them plenty of time to acclimate to the new environment.  Make sure the new cat cannot see the resident cat and vice versa.  An accidental encounter might derail the entire introduction.  When all the cats feel comfortable with the new set-up begin the process of desensitization.  Rub each cat with their own towel or soft brush concentrating on the sides of the face.  Next, introduce the towel or brush to the other cat.  This allows them to smell each other in a non-threatening situation.  

When both cats accept the other’s scent without hissing, dilating their pupils or acting upset, then it is time to move to the next step.  Allow each cat to explore the other cat’s room on their own.  Make sure the cats do not see each other when they are moved.  Keep rotating the cats from room to room until the new cat is comfortable with the entire house.  This will take away the territorial advantage of the resident cat over the new one.  After the cats are comfortable with each other’s scent throughout the house, it is time to move to phase 2.


Now that the cats accept another cat in their environment, it is time to move into counter-conditioning them to like each other, or at least to tolerate each other.  Erect a barrier which allows the cats to see a small portion of the other.  The slit beneath a closed door works well for this.  Under supervision, feed each cat on their side of the door.  Put the bowls just close enough that they can see each other.  The idea is to teach each cat that good things happen, i.e. food, when they are in the presence of the other cat.  Slowly move the bowls closer to the door, until the cats are eating next to it.  After the meal, allow them to play ‘footsie’ under the door.  If either one shows any signs of aggression, stop the interaction immediately.  A thick towel works well for this.  Do not use your hand as the cat might redirect their aggression towards you and bite your hand.

When the cats lie on their sides and play with each other under the door, they are ready to move to the next step of counter- conditioning.  Allow them to see each other’s entire body through a screen door or by putting each cat in their own carrier.  Feed them while they can see each other.  Set up a Feliway diffuser in the area to help calm both cats.  If they eat the entire meal and seem relaxed, move the bowls closer to the screen or move the carriers closer to each other at the next meal.  If either cat seems upset, increase the distance between them.  When the cats eat next to each other, they are ready for the next step. 

Remove the barrier and feed them at a comfortable distance from each other.  Continue to use the Feliway Diffuser to spread calming pheromones in the area.  Have a back up restraint plan in place just in case one of the cats tries to attack the other.  A harness with a leash works best if the cats are acclimated to them.  You may also use a thick blanket, cat net or a Super Soaker to break up a fight.  A word of caution, never use your hands to break up a cat or dog fight.  I have seen many horrible injuries from that.  Slowly move the bowls closer together and increase the amount of time the cats see each other.  Always supervise their visits until both cats are comfortable with each other.  Reward good behavior with food, treats or toys. 

***I always try to desensitize and counter-condition the cats without resorting to drug therapy.  I save the drugs for the poor cats who were introduced improperly and now have additional problems that must be addressed.  It should also be clear that placing the cats together and hoping they figure it out on their own is neither appropriate nor likely to succeed.       

Published by kristennelsondvm

Dr. Kristen Nelson grew up on a farm in Watertown, Minn., where she developed a deep love for animals of all kinds. She received a Doctor of Veterinary Medicine degree from the University of Minnesota, College of Veterinary Medicine. Kris then completed a small-animal internship at the prestigious Animal Medical Center in New York City. In addition to writing and speaking, she cares for small and exotic animals in Scottsdale, Az. Dr. Nelson is widely quoted in the media. Her credits include Ladies’ Home Journal, USA TODAY, the Los Angeles Times and numerous radio and television interviews. Dr. Nelson has written two books, Coated With Fur: A Vet’s Life and Coated With Fur: A Blind Cat’s Love. Kris and her husband Steve share their home with rescued cats, birds and a dog.