When cats don’t recognize each other and become aggressive, it’s known as feline non-recognition aggression.
Feline non-recognition aggression is a phenomenon that occurs when one cat is suddenly aggressive toward another cat in the household after a period of separation.
This may happen when one cat has spent some time outside the home and is viewed as a stranger or a threat by the cat that remained at home.
The main thing that causes feline non-recognition aggression is unfamiliar scents on the returning cat, such as the scent of other cats or unfamiliar people.
This is most commonly seen after your cat visits the vet and returns home to the other cats in the home.
The new smells picked up at the vet’s office can make the returning cat seem like an intruder to the other cats in the household.
Some of the most common reasons why cats may not recognize each other and begin to act aggressively toward one another are:
1. Change in Scent
Cats have highly sensitive noses and rely heavily on scent to identify their family members.
When one cat spends time outdoors, they can pick up unfamiliar smells and odors, making it difficult for the other cats at home to recognize them upon their return.
This can cause them to view the returning cat as an intruder, leading to non-recognition aggression.
To prevent this, you can try rubbing a towel or cloth on all of your cats and exchanging them so that they get used to each other’s scents.
It can also be helpful to reintroduce them gradually, allowing them time to smell each other from a safe distance.
2. Long Periods of Separation
Extended periods of separation can also cause non-recognition aggression.
When two cats are separated for an extended period, either intentionally or by chance, their scent recognition may diminish, leading to unexpected attacks.
For example, if one of your cats goes to the groomer and comes back smelling different, the other cats may not recognize them right away.
To prevent this, try to reintroduce your cats gradually by placing them in separate rooms and swapping their blankets.
This will allow both cats to reestablish their scent and reduce the chance of aggression when they are allowed to meet.
3. After Vet Visit
Cats can also experience non-recognition aggression after a visit to the vet.
This is likely due to the change in scent due to veterinary procedures and medications that change the cat’s aroma, as well as the stress associated with the visit.
To prevent this, try to keep your cats separate during the first few hours after the vet visit, allowing the returning cat time to settle in and smell familiar surroundings.
You can also try spraying your returning cat with a calming pheromone spray to help ease any anxiety.
4. Physical Discomfort or Illness
Cats are experts at hiding signs of pain and illness, which makes it challenging to recognize when they are feeling unwell.
If a cat is feeling unwell or in pain, they may show aggression out of frustration or as a way to protect themselves.
This behavior is common when a returning cat is ill or behaving abnormally and is perceived as a threat by other cats in the home.
In my experience, Cleo tends to get quite aggressive towards us and other cats in the house when she is feeling under the weather.
To avoid this, try to monitor your cat’s behavior and seek medical attention from a veterinarian if necessary.
After undergoing a procedure, the scent of the cat can often be different, even to other cats in the house, making recognition difficult or impossible.
This smell after surgery can confuse cats in the house, causing them not to recognize each other.
When your cat returns from the vet, reintroduce them to each other slowly or keep them apart for a few hours or a day to give the scents time to normalize.
Cats are creatures of habit, and any change in their environment can cause stress and anxiety.
The added stress from new people, new pets, or other stressors can ultimately cause non-recognition aggression.
And the truth is even if your cat is not a new pet if they come home with a new scent, they can be seen as a stranger to the other cats in the home.
When introducing a cat to other cats in the home after coming back from outside, take the time to introduce them slowly.
Don’t force the cat to interact if they don’t feel ready, and create spaces for your cats to separate or retreat until they feel comfortable.
7. Territorial Disputes
Cats may become aggressive with each other when they perceive another cat as a territorial threat, which can occur when a cat returns home carrying unfamiliar scents.
It’s important to provide separate areas for each cat to eat, drink, sleep, and play, especially after vet and grooming visits, until their scent is back to normal.
This can help prevent territorial disputes and reduce the likelihood of non-recognition aggression. Try to give each cat plenty of one-on-one attention to prevent any feelings of jealousy or competition.
Here’s a video of Jackson talking some more about aggression in cats:
How To Prevent Non-recognition Aggression in Your Cats?
Preventing non-recognition aggression in your cats is all about staying ahead of the fights before they happen. Some of the ways to avoid it include:
1. Scheduling Vet Visits for all Cats at The Same Time
Bringing your cats to the vet or groomer at the same time can minimize the chances of non-recognition aggression.
This is because they are exposed to the same scents outside, which reduces the possibility of one cat returning home with a different smell than the other.
It’s also best to keep your cats in separate carriers so they can’t fight or interact during the car ride.
2. Scent Swapping
Cats rely heavily on their sense of smell to identify familiar and unfamiliar territory and other animals.
Rubbing a soft cloth or blanket on one cat and placing it in the other’s space will allow them to familiarize themselves with each other’s scent before they meet face-to-face.
Exchange their blankets, toys, or bedding to encourage more natural and relaxed interactions.
3. Shared Grooming
One of the ways you can prevent aggression between your cats during reintroduction is by promoting a shared group scent.
An easy way to do this is through shared grooming. Groom both cats with the same brush to mix their scents.
This can create a shared group scent that can promote acceptance between your cats.
You can also try to play with them using a toy or treat to distract them from their possible negative reaction.
4. Slow and Gradual Introductions
When introducing a new or returning cat who is coming from outside, do it slowly.
Begin by keeping them in separate rooms and gradually increase their exposure to each other.
This way, they have time to adapt and recognize each other’s scent without immediately feeling threatened.
This can also allow you to observe their behavior and intervene if any aggressive behavior does occur.
5. Using Feliway Diffusers, Stress Stoppers, Peacemakers, or Safe Space Sprays
Feliway is a synthetic version of the feline facial pheromone. Using Feliway diffusers around the house and in your cats’ main area can help reduce aggression and tension between cats.
Jackson Galaxy also has some great sprays that can help to reduce stress and aggression between your cats, such as Stress Stoppers, Peacemakers, or Safe Space Sprays.
These are simple and effective ways to keep your cats calm and happy in their environment.
6. Avoiding Major Changes
Cats rely heavily on their sense of smell to recognize their own kind. Thus, any changes that alter their scent can lead to confusion, anxiety, and aggression.
Try to minimize major changes that can impact the scent of your cat. Examples of such changes include grooming, vet visits, traveling, and pet sitting.
If you choose to pet-sit one of your cats, it may be more advantageous to have all of your cats cared for in the same area by the same caretaker.
If these changes are unavoidable, consider bringing your cats along so their scents change together. Also, try to limit the duration of these changes to reduce the impact on their scent.
7. Positive Reinforcement
Use positive reinforcement to help with non-recognition aggression.
When your cats are in the same room, reward them for their calm behavior. Praising them, giving treats, or playing with them can all be effective ways of reinforcing good behavior.
This way, they associate each other’s presence with pleasant and happy experiences.
Dealing with your cat’s non-recognition aggression when it happens
Feline non-recognition aggression is a distressing problem for both the cats and humans involved.
To fix and deal with it when it happens, try to keep calm and avoid shouting or reprimanding any of your cats, regardless of their reactions.
- Don’t let your cats fight it out
- Separate your cats as soon as possible
- Put the cat that’s being attacked in a separate room
- Don’t try to soothe the aggressive cat; it may reward their behavior
- Keep the aggressor on a harness for safety
- Counter-condition the more aggressive cat by offering food only when the cat being attacked is in sight
- Make sure all your cats are spayed and neutered to help reduce aggression
- Go back to the idea of scent swapping I spoke about above. Switch your cat’s toys, brushes, or something else with each other’s scent to help them become familiar with each other’s scent
- Give all your cats lots of love, attention, and playtime; to reduce feelings of competition and jealousy.
Here’s a video from Jackson about reintroductions with your cats and dealing with cat fights:
How to prevent non-recognition aggression in cats after vet visits?
Nonrecognition aggression in cats is a common issue after vet visits, but it can be prevented through these measures and in this order:
1. Separate your cats
After returning from the vet, try to keep your cats separated for a few hours.
During this time, ensure they have no visibility to each other.
This allows your cat coming from the vet to readjust to their home environment and gives them the opportunity to shed any scents they may have picked up from the vet’s office.
2. Swap your cats’ scents
If you have a towel in the carrier, use it to pet the other household cats to spread the scent of the cat that went to the vet.
Groom your cats with the same brush to mix their scents, or use a separate cloth for each one and swap them around in both cats’ spaces, allowing them to get used to the other’s scent before meeting again.
Yes, this is sort of like reintroduction.
3. Use calming products
Using Feliway diffusers around your home or sprays such as Jackson Galaxy’s Stress Stoppers, Peacemakers, or Safe Space Sprays can help reduce aggression and tension between cats, even after vet visits.
4. Make sure the vet visit cat is physically able to socialize
Ensure that your cat has fully recovered from sedation or anesthesia, if they had any, before being allowed to co-mingle with others.
This is because the changed behavior or scent of a sedated cat can trigger aggression in your other cats.
5. Slowly reintroduce the cats to each other
After bringing your cat back from the vet and ensuring they are kept separate from your other household cats while their scents are being swapped, take a gradual approach to reintroducing them to one another.
This will help maintain a harmonious environment and facilitate a smooth reintegration process.
Encourage positive interactions between your cats by setting up a play area with toys or a treat dispenser.
Reward good behavior with treats or verbal praise and try to distract them from any negative behavior.
The reason for doing this and supervising the meet is because you want to help your cats associate each other’s presence with enjoyable experiences instead of fear and aggression.
6. Avoid punishing your cats
Do not punish either cat or show fear or anger because cats can pick up on your emotions and energy, and it might make the situation worse.
Here’s Jackson breaking down how to introduce cats in this video:
How long does non-recognition aggression last in cats?
Non-recognition aggression in cats can last from a few hours to possibly several weeks.
It largely depends on the individual cat’s temperament, their relationship with the other cat, and how their scent has changed due to factors like vet visits.
To prevent non-recognition aggression or speed up the process of your cats trusting each other again, you can:
- Carry both cats to the vet even if only one needs to be seen this way; both of them will have the same scent when they return home.
- Use familiar scents like a towel or a piece of clothing that smells like home and the other cats to rub on the cat who’s coming from the vet to make the scent familiar to the other cats again.
- When the cat returns home, keep them separated from the other cat for a little while. Let them sniff each other under the door and re-familiarize themselves with each other’s scent but don’t reintroduce them until you’ve followed the tips above for scent swapping.
- Don’t rush the reintroduction process. Following a period of separation, reintroduce the cats slowly, starting with short, supervised periods of time together.
- Feliway spray and other pheromone-based products like Stress Stopper, Peacemaker, and Safe Space can help reduce tension and promote a sense of calm during reintroduction.
It may take some time, but if you consistently practice these techniques, your cats should eventually become more trusting of each other and recognize their fellow family member.
If your cats’ aggressive behavior continues despite your best efforts, it may be best to seek professional help.
Speak to your vet or get in touch with a cat behaviorist who can provide tailored advice for your specific cat dynamic.
Remember, patience, consistency, and calmness are key during this process. You can do this.