Feline Non-Recognition Aggression

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by Dr. Nicholas Dodman

Dr NIcholas Dodman

I have already addressed inter-cat territorial aggression and feline redirected aggression in earlier blogs. Another type of aggression that cats can express is referred to as non-recognition aggression. What happens in non-recognition aggression (so-called) is that a cat returning from a veterinarian’s office is attacked by another resident cat with whom it was formerly friendly. No one knows what the trigger for non-recognition aggression is, though it has been suggested that it is something odd about the appearance or smell of the returning cat — who may be mistakenly perceived as foreign by the incumbent.

One of the first cases I saw involved a cat who was savagely attacked by its housemate when it was brought home after being sedated and then bathed at the local vet’s office. As soon as the carrier was opened on returning home, the stay-at-home cat launched itself at its housemate in a fierce attack. The man of the house tried to break up the fight but became subjected to ferocious redirected aggression as the cat turned its ire on to him! The man fled upstairs and locked himself in the bathroom for his own protection as the cat threw itself at the door practically rattling the hinges and remained dangerous for hours. Eventually things settled down and the man, very cautiously, came downstairs. The two cats were isolated from each other and were successfully reintroduced a few days later.

When I asked the man if he had ever seen the aggressor do anything like that previously. He thought for a moment and then remember one occasion when the victim cat was outside and came face to face with a skunk. The cat fled but not before releasing pungent secretions from its anal glands – whereupon its housemate attacked it in a similar manner. That got me thinking about whether anal gland secretions were the trigger. Perhaps a cat at the vet’s office who shoots off its anal glands in fear might transport that fear-induced odor back home and alarm the resident. When I told this theory to the owner’s wife, she asked if the fearful cat’s anal glands could be removed to circumvent similar aggressive responding in future by its housemate. I had to admit it is quite easy to remove anal glands by means of a simple relatively non-painful surgery requiring no more than two 8mm incisions on either side of the anus. She elected to have this done at her local vet’s practice and we all waited patiently for the next time the more timid cat needed veterinary attention. Alas, on the next vet visit, the resident cat erupted in aggression again when its mate was returned from the vet’s office. At least the owners were prepared for the worst this time, and just as well. So anal gland secretions were not involved – at least, not in this case.

I pondered over the role of the lingering odor of pet shampoos – but some cats I saw with this condition had not been bathed. Then I wondered if the trigger might be something like the smell of alcohol, which vets often use to cleanse the skin prior to injections. I could not validate that either. Next I thought it might be the behavior of a semi doped-up cat returning from the vet’s office without having fully recovering from sedation. With this in mind, I had people keep susceptible cats apart from their housemate until they were fully recovered. That didn’t work either. I was, and still am, at a loss to explain this phenomenon but it surely happens – and many times over unless lengthy separation and gradual, supervised reintroduction of the two cats — as in the treatment of inter-cat territorial aggression – is not practiced.

Though I feel that I have ruled out the odor of anal glands, shampoos, and the smell of alcohol as triggers, I still remain suspicious that odor of some sort is somehow involved. Cats do not have a sense of smell as powerful as a dogs but is certainly very acute and much greater than our own. A cat has – by some accounts – 125 million smell receptors in its nasal cavity as opposed to our measly 12 million. And cats have a vomeronasal organ – a nose within a nose, so to speak – which can detect minute traces of pheromonal odors. Contrary to what was popular opinion, cats are “macrosmatic” species who use olfaction as a powerful guide to their environment. Video-graphically documented experiments have revealed that cats investigate their housemates and environment by active sniffing for considerable amount of time, never mind odors they passively pick up in the air. If smell is that important to cats in signaling all manner of things, both good and bad, I feel sure that it is somehow involved in non-recognition aggression. Resident cat may think, it certainly looks like my mate, it sounds like my mate … but it doesn’t smell like my mate. Intruder! Must be vanquished. At least that’s my best theory to date.

The bottom line is that if you have a cat that has, in the past, attacked another cat returning from the vet’s office, you must expect it to happen again and take necessary measures to prevent future catastrophe’s, which might otherwise lead to relentless, ongoing feuds between you cats. Those measures include long-term (days) separation of the 2 cats across a closed door until you are sure it is safe to let them be together again. As I alluded to at the beginning of this epistle, an ounce of prevention is always worth a pound of cure.

Prevention of this troubling condition is better than cure, as this condition does tend to recur with each veterinary visit.

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