Perhaps you have been following the recommended procedures for introducing a new cat to your resident cat, but things aren’t going well. Maybe you took one of your cats to the veterinarian and since returning the other cat has been treating him like an intruder. Or it may just be that you want to go the extra mile right from the beginning when adding to your feline family. Regardless, clicker training is an excellent tool to help your cats get along. 

If you aren’t familiar with clicker training, please see our article Cat Clicker Training Tips. You will first need to “charge” the clicker. This is simply done by clicking and then giving a treat to your cat. The cat does not need to do anything in particular – you are teaching the cat that the click sound is followed by something good. Do this in a quiet, distraction-free environment. Repeat several times. Once you click while your cat is looking away and he orients toward you at the sound you can be secure that he understands and move on to working with the cats.  

Below are the steps to follow, starting with the cats being fully separated. It is not always necessary to begin at this point; if your cats are not fighting, their tension is mild, and there are no other stress-induced behaviors (eliminating out of the litter box, inappetence, becoming reclusive, etc.) you can try beginning at the point where your cats are currently comfortable and progress from there. Baby/pet gates are encouraged for all steps. If one (or both) cat is apt to jump over the gate, stack another on top of the first to create a tall barrier in the door frame. The door can instead be opened just an inch or two for steps 1 through 5 if a gate is not yet on hand or if preferred. For clarity’s sake, the reactive cat will be called RC and the neutral cat will be called NC.  

  1. Open the door that is separating them. Click as soon as RC looks at NC, give a treat by tossing/placing it a few inches behind her (to reset and to ease potential tension), and close the door. Wait a few seconds and repeat. Do this several times and then end the session. Do two more sessions and then go to step 2 or do as many sessions as needed for RC to not hiss, growl, or act aggressively immediately upon seeing NC and then go to step 2. 
  2. Open the door that is separating the cats. Wait until RC has looked at NC for one to two seconds and then click, give a treat (as above), and close the door. Wait a few seconds and repeat. Do this several times and then end the session. Do three or four more sessions and then go to step 3. If RC is hissing, growling, or acting aggressively then go back to step 1 and progress more slowly. 
  3. Repeat step 2, waiting two or three seconds after RC looks at NC before clicking, treating (as above) and closing the door. If RC looks away from NC before that time has elapsed, click and reward that behavior – he is not behaving offensively and that should be reinforced.  After several sessions, move to step 4. 
  4. Open the door separating the cats. Click and give a treat following any neutral, relaxed, or friendly behavior of RC’s: blinking at NC, air sniffing, sitting or lying down with a relaxed posture, looking away, etc. If RC simply looks at NC, click and then treat every few seconds. The treat can now occasionally be given directly in front of RC. Close the door after about ten seconds, wait about 30 seconds, then repeat or immediately close the door if RC starts to become tense, hiss, etc. and go back to step 3. 
  5. Repeat step 4, gradually increasing the length of time that the door is open. After several sessions of relaxed behavior for about 15 minutes, proceed to step 6.
  6. Open the door. Spend a few minutes clicking and treating appropriate behaviors. Toss the final treat for RC several feet behind him. When he finishes the treat, before he approaches the door again, remove the gates. Click and reward RC as soon as he looks at NC. Do not yet attempt to increase duration of behaviors before rewarding; click and reward as soon as he looks at NC, even if it is immediately after he finishes eating a treat. The cats are free to move about freely now, but they must decide to do so on their own. Do not force one cat to go near or see the other. Keep the session brief – a few minutes if the cats are relaxed and you are clicking often or as short as a few seconds if either cat is tense or RC won’t eat the treats. 
  7. Repeat step 6 as often as desired, following the same original procedure of gradually increasing the length of time they are together.  

If each cat is reacting negatively to the other, you will likely need to clicker train them both. This is obviously more complicated and will be much easier if two people are involved, one taking responsibility for one cat each session. Each cat should have his own clicker. If you must work solo with two cats, each cat needs a unique marker, such as a clicker for one and a verbal marker (“yes”) for the other. The alternative marker needs to be charged just like the clicker.  

If you would like information from an Anti-Cruelty Society Behavior Specialist regarding this behavior topic, please call 312-645-8253 or email

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