Why Do Cats Lick & Groom Each Other? Hint: It's Probably Not What ...

If you’ve ever had more than one cat under your roof, you may have noticed a feline behaviour crop up where – every so often – one cat will begin to lick and groom another.

At this point, either the first cat will continue to groom the second on his or her own, or the second cat will join in, grooming the first cat back until the two begin licking and grooming one another for a little while.

If you’ve ever seen this behaviour firsthand, you’ve been lucky enough to be a witness to the incredibly neat behaviour of domestic cat allogrooming.

Allogrooming – or social grooming between two or more members of the same species – is something that many species do.

I’m sure you can already think of an example or two that feels similar to two cats licking one another – monkeys picking fleas and lice out of each other’s hair, for instance.

There are many commonalities between allogrooming behaviours from one species to the next, but there are also differences, so what I’ll be talking about here are specifically facts and theories scientists have discovered and refined through studying allogrooming in the domestic cat world.

Facts We Know About Allogrooming in Domestic Cats

There are a number of things we know to be true about allogroming in domestic cats. They are the following:

1. Both indoor and outdoor cats allogroom.

While I’m not saying they both allogroom at the same rate or frequency (house cats typically allogroom more since they are in closer proximity to other cats, and that’s a factor in whether there will be more allogrooming), still – both indoor and outdoor cats engage in allogrooming behaviour.

2. Cats that are spayed and not spayed, neutered and not neutered allogroom.

Spayed and neutered cats, as well as cats that haven’t been neutered or spayed, will all engage in allogrooming behaviours.

Again, there are differences in frequency and likelihood of spayed vs not spayed and neutered vs not neutered cats grooming another cat, but it’s still true that all types do allogroom.

3. Allogrooming occurs regardless of a cat’s gender – and regardless of the gender combination.

Male and female cats both allogroom – though male cats seem to groom other cats more than female cats seem to groom other cats.

Male and male cats allogroom, male and female cats groom each other, and female and female cats also lick each other clean in allogrooming sessions.

That being said, male and male allogrooming sessions are most popular, with female and female is likely the least frequent allogrooming gender combination to take place.

4. While two cats may regularly engage in allogrooming together, one cat will typically give the majority of the grooming.

You’re likely to have noticed this already if you regularly see allogrooming happen in your home.

In the vast majority of cases, there will be one cat that does a lot more of the licking and grooming to the other.

The cat that is more often than not on the giving end is not a coincidence either…

5. Dominant, confident cats are more likely to allogroom less-dominant, less-confident cats.

A cat that is the socially higher ranking and more confident is more likely to be on the giving end of the grooming.

A socially lower ranking cat is more likely to be on the receiving end. This isn’t always true, but more often than not, it is.

Thus, there’s a co-relation that’s been found:

6. Cats typically receive more grooming from cats who are aggressive toward them.

If one cat is typically the victim of another cat, that cat will also typically receive more grooming and licking from the dominant aggressor cat due to the dominance factor playing out in allogrooming.

7. Two conditions co-relate with more allogrooming: higher numbers of pairs of cats living in the same space, and less aggressive behaviour between cats.

An increase in the number of pairs of cats is positively co-related and will thus increase chances of allogrooming taking place.

An increase in mean, aggressive behaviours amongst cats has a negative co-relation with allogrooming – the more aggressive behaviours there are the less chance there is of allogrooming taking place.

Scientific Studies About Domestic Cat Allogrooming

While there have been a few studies done on the topic of domestic cat allogrooming, the research does seem to be a little thin in this department quantity-wise.

Of the research out there, Ruud van den Bos published an excellent paper in 1998 called “The Function of Allogrooming in Domestic Cats (Felis silvestris cams); a Study in a Group of Cats Living in Confinement,” and it’s where I’ve pulled the vast majority of facts for this article from.

I managed to find a full PDF version of the study online, so in case you’d like to go over it yourself, it can be found here.

The points from the van den Bos’ paper I find most interesting are as follows;

With allogrooming, the vast majority of interactions (94%) began with one animal approaching or inviting the other animal – not when animals were already sitting or lying together.

The majority of interactions (91.6%) were unidirectional (one cat licked and groomed the other).

Allogrooming usually occurred in the head-neck area.

In most cases (69.9%) allogrooming ended when one animal moved away, as opposed to the two staying near one another.

A few cases (12%) ended with one animal fleeing the other.

Overwhelmingly, groomers either stood (43.6% of the time) or sat up (45.1% of the time) during allogrooming sessions, while groomees often sat (46.6% of the time).

Cats that groomed themselves (self-groomed) more and for longer periods of time typically also engaged in allogrooming sessions more frequently and for longer periods of time as well.

In this experiment there were 14 male cats and 11 female cats (1 female who was rarely present). Of the allogrooming sessions, 54 (65.1%) were two males, 26 (31.3%) were males with females, and only 3 (3.6%) were two females together. Neutering and spaying likely played a part in this, however – especially since female cats typically engage in allogrooming behaviour much more when they are in heat.

Male cats nearly always (90.4%) acted as initiators.

Male cats were more active groomers, both in allogrooming situations and in terms of grooming themselves.

More often (78.6% of the time) higher ranking cats were the ones who groomed the lower ranking cats.

Whether cats were blood relatives did not affect frequency or duration of allogrooming sessions. Thus, allogrooming does not seem to have anything to do with whether cats are siblings, parent-and-child, cousins, or relations of any kind.

What Domestic Cat Allogrooming is Not

Allogrooming in domestic cats is not about hygiene. Or at least, not exclusively and/or primarily about hygiene and cleaning.

If it was only about hygiene, there wouldn’t be such enormous differences in behaviour from gender to gender in cats, as well as in terms of social hierarchy.

Obviously, there has to be something more important at play here than hygiene.

Allogrooming also can’t be about weaker felines establishing a relationship with dominant cats who then may be able to take care of them, since most allogrooming is instigated and carried out by dominant cats rather than those that are lower rank.

For these two reasons, allogrooming doesn’t seem to be about affection either.

If it was, it would make sense that dominant and submissive cats, and male and female cats would all be relatively equally giving of allogrooming to other cats.

The last theory that is unlikely to be true is mentioned in the study I’ve referred to’s discussion.

Allogrooming also doesn’t appear to be a tool to reduce stress that may have come about because of conflicts or being in close proximity to other animals, either.

The why comes to down many reasons, the most swaying, in my opinion, coming down to the fact that if allogrooming was merely about reducing stress in the group, there should be little to no difference whether dominant or less dominant cats are the ones to instigate and carry out allogrooming.

But there is a huge difference – dominant cats are almost always the instigators and the ones to lick and groom lower ranking cats. So again, there appears to be more to allogrooming than stress reduction.

Our Best Theory: Why Cats Lick & Groom Each Other

If none of these theories is likely to be true, what’s the most likely reason that explains why cats lick and groom each other?

Ruud van den Bos believes our best theory is as follows:

Domestic cat allogrooming is likely a way for cats to redirect pent-up aggression and to reaffirm dominance in a way that’s far better (for the group) than doing so through aggressive and even violent behaviours.

As van den Bos aptly points out: “A cost-benefit analysis for groomer and groomee suggests the following.

The groomer would enjoy the benefit of not engaging in costly overt aggression in order to maintain its position, the groomee the benefit of not being attacked by its opponent” (van den Bos 1998).

Thus, our best explanation for why cats lick and groom other cats has more or less everything to do with aggression and dominance, and very little to do with anything else.

It’s a way for a (typically more dominant) cat to relieve pent-up aggression and tension, and for that cat to maintain it’s position as higher up in the hierarchy in a way that is physically safer for the less dominant cat than the alternative (i.e. being attacked), which is more beneficial for the group.

As I stated in the “Facts We Know About Allogrooming” section, less aggressive behaviour co-relates with more allogrooming, but this could simply be because allogrooming causes there to be less aggression on the part of dominant cats – since they are ridding themselves of their pent-up aggression through the process of grooming the more submissive cat.

So while it definitely doesn’t seem to be an action of love, it does seem to yield a lot more peace and harmony in the group.

Not quite the adorable explanation you were expecting, but it does seem to fit, doesn’t it?

Thoughts on Cats Licking & Grooming One Another?

Have you ever seen two cats lick & groom one another? What did you expect this behaviour to mean?

Have you ever had a pair of cats under your roof who regularly allogroomed? Was one cat usually the one to instigate and carry out the grooming? Was this cat the more dominant of the two? The more confident?

Does the theory outlined as the best working theory in the scientific study make sense to you?

Does it align with the behaviour you’ve seen in your multi-cat home? Does it clarify anything you were wondering about? Or do you think there’s another theory that fits better?

Really looking forward to hearing your thoughts on this behaviour in the comments below!