Published by: Ingrid King. Last Updated on: July 9, 2023 by Crystal Uys

Two cats playing outside

Your two cats are best friends. They play together, groom each other, and sleep curled up with each other. Then one day, you take one to the vet’s for a check up. When you return from the clinic, instead of receiving a warm welcome, the cat who stayed home hisses and attacks the other cat. Your two former best friends have turned into sworn enemies, and your formerly peaceful home has turned into a battle zone.

Aggression between cats is always a distressing problem for the cats and the humans involved. Whether it’s play aggression, petting aggression, or redirected aggression, dealing with feline aggression is stressful and requires commitment, staying power, and the help of experts such as your veterinarian and/or a feline behaviorist.

The cause of on-recognition aggression is not entirely clear, and the bad news is that it’s not easily fixed.

Possible causes of non-recognition aggression

  • The returning cat smells different. He may have absorbed smells from the environment at the veterinary clinic. If he had anesthesia, the drugs may have temporarily altered his body chemistry, which may also result in a different smell to sensitive cat noses.
  • The smell of alcohol or other medical smells may remind the cat who stayed at home of a negative experience.
  • The returning cat may have released his anal glands while he was in route to the vet’s, or at the vet’s. While this may seem simply be a stinky mess to us,  to the other cat,  it may signal fear and danger.
  • The returning cat may behave abnormally. If he hasn’t fully recovered from anesthesia, he may wobble as he walks. This may be perceived as a threat by the cat who stayed home.

Unfortunately, the attacks resulting from non-recognition aggression can be quite vicious, and can also be redirected at the humans in the household.

Image Credit: rihaij, Pixabay

How to deal with non-recognition aggression

  • Never let the cats fight it out. Cats don’t resolve their issues through fighting.
  • Interrupt the aggression in a way that keeps you safe. Clap your hands, toss a toy, throw a blanket over the cats, or separate them by pushing a piece of carboard between them.
  • Try to herd the aggressor into a separate room and close the door. This gives both cats a chance to calm down. This can take several hours, and sometimes, days.
  • Don’t try to soothe the aggressive cats – leave him alone to give him a chance to calm down. An agitated cat may continue to be aggressive and redirect that aggression against the humans in the household.
  • Give the cats a chance to familiarize themselves with each others’ smells and sounds after they have calmed down. In severe cases, you may need to start a gradual reintroduction, as if they had never met before.

How to prevent non-recognition aggression

Nobody seems to know for sure how to prevent non-recognition aggression, but the following may help:

  • Make sure the returning cat has fully recovered from anesthesia or sedation before bringing her home.
  • Remove any veterinary odors from the returning cat. You can bathe the cat if this doesn’t add more stress, or use unscented baby wipes. Follow this by rubbing something with the cats’ regular scents on them, such as a blanket or favorite toy. Rub both cats with this item.
  • Keep the cats separated for a few hours to give them a chance to get used to each other’s sounds and smells.
  • Reward the cats with treats and praise once they interact in a friendly manner.
  • Use holistic remedies such as Stress Stopper for the cat who is going to the vet’s, and use Stress Stopper and Peacemaker for both cats once he returns home.
cat being fed a cat treat or cat food by hand
Image Credit: Jakub Zak, Shutterstock

Some experts advise to take both cats to the vet together, even if only one cat needs veterinary attention. There is no evidence that this helps prevent non-recognition aggression, but it may be worth a try if this has been an issue for you in the past.

Featured Image Credit: Christel SAGNIEZ, Pixabay

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