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Dear Most Esteemed and Knowledgeable Kitties:

My two 8-month-old brother cats, are usually very loving and clean each other. Recently I noticed one of them won’t stop crying at night on our bed; then I caught the other one grabbing his neck with his teeth and apparently trying to mount his brother! The little brother had tears and was crying! I pulled his brother off him, but then he kept this up all night. I’m scared! Can my cat actually hurt and try to mate with his brother? I never thought this possible. Please help!


Dear Most Esteemed and Knowledgeable Kitties:

I have two cats, both male and altered. They are approximately 4 and 5 years old. I got both of the cats at the same time. The normally docile cat is mounting the other male cat. The other cat’s rectum looks red and inflamed. Is it actually possible penetration occurred? Is a vet visit necessary?


Thomas: I’ll start this one out. As the resident expert on male cat behavior, I’m exceptionally qualified to answer these types of questions. When male cats mount one another, it’s in an effort to establish dominance. Animal behaviorists refer to this as sexual aggression.

Siouxsie: We’ve seen this behavior not only in cats, but in the dogs, goats, and chickens we live with. Sometimes female goats will even mount one another to show dominance!

Dahlia: Sade, you don’t mention if your cats are neutered. If they’re not, neutering will serve to gradually decrease this behavior. However, if they are neutered but it only happened recently, give it time. It takes several weeks after neutering for the male’s testosterone levels to decrease to the point where there is little to no sex or dominance drive.

Thomas: Jenny, you said your cats are neutered, and presumably since they’re 4 and 5 years old, they’ve been neutered for quite some time. This is a pretty clear case of solely dominance-based behavior.

Siouxsie: But you both should know that neutering a male cat doesn’t automatically turn him into an it. Males still have some sex hormones circulating in their blood, even though that level is very low.

Dahlia: Like humans, cats have chromosomes that determine their sex. Male cats have an X and a Y chromosome, and female cats have two X chromosomes. The cat with an X and a Y chromosome has its brain bathed in testosterone as it develops in the uterus, which causes permanent changes in the structure and chemistry of the brain. The massive increase in the amount of testosterone at puberty fully activates these changes, but they don’t go away with neutering.

Thomas: Therefore, a male cat is always male and will continue to demonstrate some male behaviors even after he’s neutered.

Siouxsie: We’re 99% sure that anal penetration does not occur when male cats mount other males, because we don’t think it would be physically possible. Cats’ mating practices are designed to introduce the penis into the vagina, and the vagina is positioned lower than the anus.

Dahlia: In order for penetration to occur between male and female cats, the female has to assume a swaybacked position that points her genitals upward, and then she has to move her tail aside. This behavior is instinctive in female cats and typically it only occurs when the female is in heat and receptive to the male’s mating behavior.

Thomas: When male cats mount other males, generally the one on the bottom won’t “assume the position” because he doesn’t have the same hormonally and instinctually based response as the female. And generally, male cats don’t get erections when mounting other males.

Siouxsie: There are some things you can do to reduce or eliminate the mounting behavior, however. Dr. Nicholas Dodman, author of a number of animal behavior books including The Cat Who Cried for Help: Attitudes, Emotions, and the Psychology of Pets, says that using a pheromone treatment like Feliway (which comes in spray or diffuser form) can help to reduce the aggression that leads to this behavior.

Dahlia: Applying androstenol (a sex attractant for pigs) to the rump of the victim can also discourage unwanted attacks. I’m not sure how that would work, but maybe your vet would have a clue.

Thomas: You could also make the aggressor wear a large, loud bell so the victim can hear him coming and get out of the way. But remember, we cats can be pretty creative about removing such devices and learning how to move quietly even with a bell attached to our collars!

Siouxsie: Dodman also says that medicating the aggressor with progesterone-like compounds can be effective for temporary management of the behavior.

Dahlia: And finally, Dodman says that SSRI medications like Prozac can be used to manage aggressive behavior. We’d suggest you try the other methods first before resorting to psychopharmacology. But remember, if nothing else works, antidepressants or anti-anxiety medications can be an option.

Thomas: There are things you can do to stop this aggression behavior, and we hope that you’ll find one or more of these tactics to be helpful in managing your kittyboys’ behavior. Good luck, Sade and Jenny, and please let us know how things turn out!