Sexual Aggression in Neutered Cats

Even a neutered male cat can make life miserable for his female housemate. And fighting with neighborhood males can persist, too. Here's why.


Unless you’re planning to breed your male cat, there are several very good reasons for you to have your pet sexually neutered at some point during the first six months or so of his life. Most importantly, the procedure will prevent his contributing to the worldwide problem of feline overpopulation.

Neutering will also eliminate or at least reduce the occurrence of several undesirable sex-related behaviors. These include, for example, roaming, scrapping with rival male cats in the neighborhood or in your own home; staking out territory by spraying foul-smelling urine throughout your home and property; and persistently attempting to mount and sexually engage a female cat in the household, whether or not she is willing to cooperate.

Some of these sex-related activities, however, may persist even after a cat has been neutered. The male sex hormones — chiefly testosterone and its derivatives — tend to start being secreted when a cat is four to five months of age, and the animal will begin to show an interest in females two or three months after that.

Neuter Your Cat By 6 Months Old

“That’s why we recommend that a cat be neutered by the time he is about six months old,” says Nicholas Dodman, BVMS, director of the Animal Behavior Clinic at Tufts. “If you let a male go unneutered, he’ll have a lot of testosterone circulating in his body, and he’ll continue to be very interested in females. He’ll smell a female in heat from several blocks away, and he’ll be very eager to get out of the house and go after her. And if he’s not allowed to go outside, he is likely to start humping something else, such as a stuffed toy, a table leg, a pillow — anything he can get at.”

Until months or even years go by, a neutered male cat may continue to express himself sexually with a female cat living under the same roof, even though she has been spayed. “He sees this female wandering from room to room,” says Dr. Dodman, “and he’ll run after her in the same way he would in a true mating sequence.” He describes what happens next in a behavior pattern motivated by what he refers to as residual maleness: “The female will be terrified. She’ll run and try to hide. But the male cat finally jumps her from behind, and there’ll be fur flying. And then he’ll bite into her neck, drag her to the ground, pin her there, and may even attempt to mate with her.”

Although neutering gets rid of various unwanted behaviors — including rapacious mounting activity — in 90 percent or so of male cats, Dr. Dodman notes that about 10 percent of cats will continue to display the behaviors. Some of these cats will also go on spraying urine as a means of marking their territory for a period of time — perhaps permanently — following the procedure. “So owners should know that, in some cats, neutering does not completely turn off the sexual lights,” says Dr. Dodman. “Instead, the procedure sort of turns the dimmer switch way down, but there’s still enough of the male behavioral instinct remaining to be problematic.”

This variety of feline sexual harassment poses little if any threat to the physical well-being of the assaulted female, he points out. But it can certainly be psychologically damaging to her, making her constantly wary, nervously in fear of her male companion’s next attack. “It disrupts the household,” says Dr. Dodman. “You don’t want to go on living in a place where a female is constantly afraid of being attacked. That’s havoc, and that’s why a cat owner should make every effort to curb this behavior.”

Medication Can Help Sexually Aggressive Cats

An array of pharmacologic interventions are available that may be effective in reducing a neutered male’s inclination to assert sexual dominance. However, advises Dr. Dodman, before trying any of these pharmaceuticals, it would be worthwhile to have an offending male cat examined to make sure that the neutering operation that he underwent was performed properly.

It is possible, he says, that, during the operation — due to an oversight by the surgeon — only one of the cat’s testicles was removed. If that is the case, an injection of a hormone called gonadotropin-releasing hormone (GnRH)) will reveal the presence of any residual testicular tissue by causing a surge in testosterone. “This is very rare,” Dr. Dodman notes, “but it does happen. Sometimes, for example, one testicle was in the normal location but the other was in the abdomen, inaccessible to the normal neutering procedure.” Ultrasound can also be used to make the diagnosis.

If it is determined that a cat was successfully castrated, the pharmacologic substances that may be helpful in curbing his persistant sexual aggression include clomipramine and fluoxetine, which can reduce the obnoxious behavior.Although such drugs are gaining popularity for the suppression of unwanted sexual drive, they must be used only under the careful supervision of a veterinarian.

Dr. Dodman sometimes uses fluoxetine to treat overzealous male cats, but he sometimes opts instead to use topical androsterone, a pheromone produced by males, on the females in the household. He explains: “If you apply this pheromone to a female cat’s rump every other day or so with a small cloth and a male approaches her, he’ll suddenly stop short, arrested by this powerful scent of maleness, and he’ll turn away as if to say ‘Oh, excuse me, sir … I must have confused you with someone else.'”


  1. Dr. Dodman,

    Which topical androsterone pheromone do you recommend? My male cat will not stop attacking his older sister.

    • So,if anyone noticed that the author/writer of this piece was Estaff? Dr. Dodman was just quoted in this article. I repeat, Dr. Dodman did not write this article, therefore Dr. Dodman won’t be seeing nor responding to any of your questions; which is unfortunate, as I need an answer as well. This article is 7 years old and I’d be very surprised if any of the people involved even remember this article at all.

    • I have the same problem! My large orange tabby male will not leave my female alone. They had both been nuteted and spayed. They used to be best friends! So confusing!

  2. Yes, where do you get it and is it a certain strength. I tried Hog’s Mate and it did not work But I read on Cornell that they use a product named Signa, I believe but I have not been able to find it. do you get it at a compounding shop We need it desperately for our one yr old male. He torments our two females which torments us. Thank you.

  3. This is the first I’ve ever heard of feline sexual harassment! We have a male cat and are considering getting another and now I’m thinking twice about getting a female. Thanks for the information.

  4. I have a male cat age 1 yr. 3 months . He was neutered at 8 months. Today he got up on the blanket I was cover up with and started kneeding, no big deal so I thought, I notice his tail twitching every few seconds and pushed him down . He then went to cleaning his private area. I then moved my hand onto my blanket to find a small wet spot. Is this just a freak thing or do I need to be concerned of something? I’ve not caught him spraying anything. This is the first thing I’ve noticed. Please help

  5. My 3 year old neutered male all of a sudden will not leave my 4 year old spayed female alone. He is very aggressive with her and we now have to keep them separate when they used to be the closest. We’ve tried calming collars and the calming defuser spray but it is not helping. What else can I do?

  6. My cats used to be friends and now the male won’t stop attacking the female. Will spraying male pheromones on my female cat affect her when she cleans herself?

  7. I also have this issue. My boy cat – female cat were adopted together, not siblings & he does this mating ritual and she screams. The rest of the time they play constantly. I have an older female & I’ll go crazy if he tries this on her..she’s my perfect angel..where can I get this stuff?? Please help!!

  8. I have a 15 year old neutered male… he was neutered 15 years ago. In the last 6 months, he has developed aggressive urges and will attack the other males and females (usually the males) of the house and mount them against their will. He has not been this way for the last 14+ years… please help.

  9. Did anyone figure out which product to use? I am about to purchase Boar Mate Hog Spray but have no idea if the concentration or other ingredients in it are safe for cats. Please help!

  10. I have the same issue, he grabs her neck with his teeth repeatedly. The poor girl. The vet gave us Prozac – it was not successful after months. No idea which way to turn now. It seems there are many of us in this spot.

  11. I am having the same problem with my male cat. He rips the hair out of my female cats neck, it’s getting worse. I’ve had both cats since they were 16 weeks old, they’re brother and sister, now 5 years old. Both were fixed when I got them. Been using Jackson galaxy solutions named (peacemaker)seems to be working. I ordered and waiting for the solution named (Bully) in the mail.

  12. We rehomed two neutered Siamese cats aged 8 nearly 5 years ago. They are brother and sister. They had another brother from the same litter who was rehomed elsewhere because he was attacking the female. Since having this pair there have been few incidents of unwanted attention by the brother on the sister but nothing she can’t handle. However, in recent weeks he has upped his attacks on her and they are becoming nastier. I have no idea why? He sniffs where she has been sitting and follows her around until he finds an opportunity. They are house cats but haven’t had a problem for the first 4 years of living here. What has changed?

    • I am not a vet, however I believe what has happened is the removal of the dominant male has now given your other male the green light with your female.

  13. I need help. I have a neutured 6 month old tom and he is driving my 10 yr old female nuts. If the problem does not get fixed I will need to find him another home.

  14. My tom is fixed when he bothers my females i give him time out 15 minutes in the animal crate and he is doing good don’t get rid of your tom cat he will get real sick i know i had a very healthy cat gave him away and he died of a broken heart


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