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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Vet
Satisfied Customers: 32782
Experience:  University of California at Davis graduate veterinarian with 45 years of experience.
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Inter cat aggression problem between 10 month old neutered

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Inter cat aggression problem between 10 month old neutered male and 4 month old neutered female
Aloha! You're speaking with Dr. Michael Salkin
I'm sorry for the delay in responding to you. Your question came in late at night when few vets were available. I have advanced training in feline behavior and am pleased to discuss feline aggression associated with a new cat in the household. Your reading may have been exhaustive so you must pardon me if I rehash information you may already know. In any event, you may pick up a few pearls of information after reading a synopsis of the notes I use when lecturing about this behavior.

Territorial aggression, along with aspects of fear and anxiety, may be exhibited when a new cat is added to the home. Of course genetics and previous social experience with other cats play a role in how one cat may react to a new addition to the household as well. While cats often choose to avoid social altercations by maintaining social distance, some that are more bold, confident, or domineering may display offensive threats to the new cat (or vice versa). In the confined area and narrow hallways of a home, avoidance is not always an available solution so that aggression becomes more likely.

Territorial and fear aggression are best managed by desensitization and counterconditioning. Drugs may be necessary, not only to control the behavior of the aggressor cat, but also to decrease the defensive posturing and vocalizing of the cat that is being threatened. Consider the use of paroxetine (Paxil) or fluoxetine (Prozac). These selective serotonin re-uptake inhibitors are useful when you're seeing uninhibited aggressive displays that appear impulsive, explosive or excessive. Defensive signaling and escape behaviors tend to elicit chasing and aggressive attacks from the bolder cat in these situations. Providing sufficient climbing, hiding, and perching areas may allow the victim the opportunity to prevent conflicts and display less anxiety. Electronic cat doors which are opened only by the cat wearing the collar that activates the door are also a means of allowing the victim cat the opportunity not only to access the entire home but also to retreat to a safe, secure area. Unwary owners may inappropriately reward undesirable behavior by offering the aggressive cat food or attention to try to calm it down. Instead, the owner should stop the undesirable behavior with a disruptive stimulus such as a compressed air canister or water gun and then reinforce the desirable response with food, praise and petting. Feliway pheromone may be more effective in an electronic diffuser that disseminates the pheromone throughout the environment. In North America, the F3 fraction of the facial pheromone is provided in Feliway, however it is the F4 fraction in Felifriend that would be preferable since it is associated with familiarization and allomarking in cats. This product should be available from

To begin with, the owner should alternately release one cat at a time to roam in the home. Once all signs of aggression, anxiety, or hypervigilance subside, desensitization and counter conditioning can begin. If there is no significant decrease in agitated behavior within a week, medication should be considered - selective serotonin reuptake inhibitors, tricyclic antidepressants, or anti-anxiety medications may be helpful. The cats should gradually be exposed to each other in very controlled situations. This can be done with the cats in carriers or controlled with a harness and leash at opposite ends of the largest room or longest hallway in the home. During the sessions, the cats are fed highly palatable food or engaged in play. During following sessions, the cats are slowly brought closer together. By withholding food and rewards except for training sessions, each cat may learn to associate the presence of the other cat with food and play, rather than fear and anxiety. Once the cats are showing no tension at close proximity to each other during the sessions, the owner can attempt to allow them to have freedom in the same room. A high-power compression water gun may be used to interrupt unacceptable behavior by the aggressor cat. Small treats can be tossed to reinforce non-aggressive behavior. They can also be used to distract the cats and lure them to safe distances away from each other when they are close and might begin showing undesirable signs of arousal. The owners can begin allowing the cats to have freedom together in the home when no signs of aggression are shown during supervised conditioning sessions for several weeks. Initially, this should only be allowed when the owner is present in the home. At least two feeding stations and litterboxes should be available when the cats are finally allowed to roam freely in the home. They should be placed so that a cat will not be trapped or surprised when using either.
Conditioning can take months and may require considerable patience and time on the part of the owner. Cats should not be allowed to "fight it out" as these fights rarely settle conflicts and may make the situation worse. Holding the pets to introduce them is commonly attempted by owners and should also be discouraged. In some instances, the most expedient and safe way to end the conflict is to remove one of the cats from the household. For the poorly socialized cat that is extremely territorial, it may be more prudent to confine it when people visit or to avoid adopting another cat.

Good luck to you in your efforts. I hope the above will be helpful.

Thank you to G. Landsberg, W. Hunthausen, and L. Ackerman for allowing exerption of their Handbook of Behavior Problems of the Dog and Cat.
Dr. Michael Salkin and other Vet Specialists are ready to help you
Thank you for your kind accept. I appreciate it.

I'm going to check back with you in a few weeks for an update. Feel free to return to our conversation - even after rating - prior to my contacting you if you wish.

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