Vet visits can be challenging for a myriad of reasons including possible unwanted diagnoses and anxiety of our cats. By the time we get home after the vet appointment, we hope for things to calm down. Though, that isn’t always the case, especially in multi-cat homes. Sometimes the cats who are left at home seem to distrust and even fight with cats who visited the vet. Seeing our cats fighting isn’t ideal for any pet parent.
The term for this unusual behavior is non-recognition aggression. It’s what happens when one cat spends some time outside the home and upon returning is viewed by a cat still at home as a stranger and a threat. Although the most often cited examples involve vet visits, this type of behavior can also happen when a cat goes to the groomer or when a cat spends time outdoors. This phenomenon is currently believed to occur only to cats.
Causes for Non-Recognition Aggression in Cats
For years, whenever I took either of my older cats to the vet, I had a routine in place for handling their return home. I’d rub a cloth on the chin of my youngest and then I’d rub a cloth on the chin of the returning cat. By doing this, I supposedly helped my youngest recognize the returning cat, and thereby helped prevent fights between them. The routine worked relatively well for years, until suddenly when it no longer did.
My struggles with non-recognition aggression this past winter is one reason that I began doing some research on the problem. The other reason is that non-recognition aggression is one of the most common issues that cat owners seek my help as a cat behavior consultant. In extreme cases, cats that used to be friends start acting like enemies and have to be separated for years.
The earliest online article I could find on non-recognition aggression in cats was written by veterinarian Dr. Nicolas Dodman and published in 2011. He declared, “This type of aggression is something that all veterinarians should know about because it usually entails aggression of one cat to another after a visit to a veterinarian’s office.”
One possible trigger explored was that the returning cat may have expressed his or her anal glands and therefore now smelled of fear. Dodman dismissed the idea of anal glands as a trigger following a discussion with a pet parent dealing with non-recognition aggression as she continued to experience it even after her victim cat’s anal glands had been removed.
Dodman concluded that he wasn’t sure what the exact trigger was or if there even was a single trigger. He also noted that people had tried myriad measures to prevent non-recognition aggression in cats without any consistent results.
Many theories now exist about the cause(s) of this cat aggression behavior. Some experts believe it’s the strange smells that are picked up by the cat while outside the home. Another popular explanation is that after having spent the day in unfamiliar surroundings, the returning cat could smell of stress. Alternatively, the returning cat’s unusual body language might convey pain. Finally, the smells from the outside environment might remind the cat at home of its own scary experiences at the vet, the groomer, or the outdoors. Any of these situations could trigger an aggressive response.
Dealing with Cat Aggression Toward Other Cats
There are also many guesses for the solution. The most common suggestion, in addition to re-applying familiar scents to each cat, is to separate the estranged cats anywhere from 24 hours to a few days.
Unfortunately, even the combination of these two tips didn’t keep my youngest cat from attacking another of my cats after its return from the vet. Nor did these two strategies alone resolve the non-recognition aggression for my clients, and so I have continued to research the problem.
In an informal survey that I conducted of cat owners, 64% of the respondents had the most success when they brought their two cats to the vet (or groomer) at the same time so they would smell alike. Another popular idea, but which only had a 14% success rate, is to rub each cat down with a cloth that contains the scent of the cat at home. The three other marginally successful ideas were: remove unfamiliar odors (perhaps with unscented baby wipes), separate the cats for a day, or give anti-anxiety medication to the cat going to the vet/groomer.
Based on my experience this past winter, several variables need to be considered because all of them could conceivably be clues to the problem of cat aggression:
- How the returning cat reacts to vet visits
- How long it took to get the cat to and from the vet
- How long the returning cat was at the vet
- How the cat’s owner responded to returning cat
In my case, I had to take two of my cats to the vet this past winter. One of my two cats reacted with minimal stress at the vet, went to an in-town vet, and was at the vet for less than a day. Reapplying scents and separating her for a day worked.
In contrast, the other cat required anti-anxiety medication to go to the vet, went to an out-of-town vet, and was at the vet for a whole day. In her case, the solution wasn’t simple.
In July 2013, Ingrid King also wrote about non-recognition aggression in cats on her blog The Conscious Cat. In her article, she listed several ideas for cat owners to try, and it’s the combination of all of those that has worked best for me. I reapplied scents, removed familiar odors by sitting outside with my returning cat before bringing her back home after her vet visit, separated her for a week, and during that time I reintroduced my cats.
Although I have encountered cat owners whose cats have remained enemies after an incident of non-recognition aggression, the results of my informal survey showed that 80% of cat owners had successfully reunited their cats. While this is good news, the fact remains that for the remaining 20%, the relationship has been only partially restored.
Upon contacting a few of the top cat behavior experts in the world, I learned that no formal research exists on the topic of non-recognition aggression in cats. For that reason, I’m continuing to do citizen science research. If you’d like to be part of my efforts, please fill out my form on non-recognition aggression. From the results of this survey, I’m hoping to discover the predominant cause(s) of and solution(s) to non-recognition aggression.
Have you experienced non-recognition aggression with your cats before?
About the Author: Allison Hunter-Frederick is a cat behavior consultant, cat therapy handler, and pet education blogger. Her articles have been published in local and national publications, as well as on her blog, Lincoln Pet Culture. Through her business, Allison Helps Cats LLC, she uses a research-based, positive reinforcement teaching approach to help cat owners improve their relationships with their cats all from the comfort of their home.