TL;DR – no, they don’t. If you see a rabbit with nipples – it’s a female. That’s pretty much everything you need to know about male rabbit nipples. They’re like the Loch Ness Monster, Bigfoot, fiscally responsible politicians and the tracking chip in the Coronavirus vaccine. They don’t exist.
Although arguably, the myth of male rabbit nipples does less harm and ruins fewer weekends than any of the others.
Anyhow, nope, no male rabbit nipples. Thanks for coming to our TED Talk. Don’t forget to tell your friends…
Sexing The Rabbit
OK, so that’s facetious. The point is that while female rabbits are the only rabbits with nipples, they’re very discreet about them – at least before they have their first litter. So, if you’re trying to sex your rabbits before they breed, or trying to work out whether you’re paying your vet to castrate your bunny or to spay them, you could be pawing through fur for quite some time before you spot the things that might be nipples or might be blotches on an immature rabbit’s skin.
Wait, hang on – why are we sexing rabbits by establishing whether or not they have nipples? Isn’t there, y’know, an easier way?
Well, you’d think so, wouldn’t you? Manhandle your young rabbit onto their back, gently peel apart some fur at a very special place, and you should be able to see what’s what and indeed, who’s what, without having to look for the familiar pattern of 8-10 nipples that will give you a definitively female rabbit.
Except with rabbits, – especially young rabbits – it’s not that simple. To be fair, with rabbits, nothing is as simple as you’d think it would be.
If your rabbit is immature, then pulling open the fur and gawping at its genitals is less easily diagnostic than it is in some other species. In many young animals, including humans, you take a look at the genitals soon after birth, you’re fairly sure you know what you’ve got.
This if course is oversimplified in the case of humans, and can lead trans people into significant trauma over time, but the principle of genital examination to determine biological sex works reasonably well with most animals – at least as far as we know. There may well be trans rabbits, but we don’t yet know enough rabbit language to understand them if they tell us so.
But the point is that with most young animals, you’re fairly clear about what you have, fairly quickly after birth. With rabbits, it’s less simple, because both male and female genitals react similarly when examined. They protrude when exposed, and they look fairly similar. The difference you’re looking for is that the male genitals have a tiny circular hole in the end, and the female genitals a tiny vertical slit.
That might sound clear enough, but when you’re dealing with young rabbits, it’s relatively tricky to tell for certain because of a) the similarity of the protrusion, and b) probably, the pretty squirmy bunny.
So, for some less experienced rabbit-owners, the whole genital-check thing is too much like hard work, and it’s genuinely easier to look for nipples when sexing their rabbits. Of course, this only works because what’s the one and only thing we need to know about male rabbit nipples??
That’s right – they don’t exist.
If they did, then there’s no reason to think they would be a handy way of sexing your rabbits, because, again, as in most immature mammals, the nipples of male rabbits – if they existed, which they don’t – would look pretty much identical to the nipples of female rabbits.
That makes the nipple-check a relatively quick and simple way of checking whether you have a male or a female rabbit. Again, it’s worth noting that the nipples of female rabbits are sometimes tricky to spot before they’re mature and have had their first litter of kittens (Yes, we know, don’t @ us – we did mention that with rabbits, nothing is as straightforward as might be wished).
Why Don’t Male Rabbits Have Nipples?
If you’re thinking, as many people do “What gives? Male humans have nipples, how come male rabbits don’t?” – don’t panic, that’s really not a stupid question.
Most male mammals have nipples, without any of the mammary, milk-giving apparatus behind them. People of faith have wondered whether this is some sort of proof of intelligent design.
That’s not it, though. If anything, men – and other male mammals – have nipples mostly because in evolutionary terms, they are as yet too much trouble to be worth the energy of tidying away with a neat mutation. Not so much intelligent design as evolutionary untidiness. Male mammal nipples have yet to reduce the chances of any mammal passing on its genes to the next generation, so in most mammalian species, they’re not worth doing away with.
Why male mammals have nipples in the first place is more or less because at the embryonic stage of their development, males and females are built on identical principles up to a given point. Then some critical DNA differentiators kick in and change the pattern slightly between male and female members of the same species.
So, why don’t male rabbits follow suit? Why don’t male rabbits have a fine set of up to 10 nipples like their female counterparts, irrespective of the fact that they’ll never use them to feed their young?
Well, research on mice – who also, like rabbits, ditch the male nipple while the young are still embryos – suggests there’s something called a Parathyroid hormone-related Protein (PHrP, for short) at work. Release of that hormone in utero retards building work on the male nipple – which in mice at least has certainly begun in the womb – and the nipple buds fade away to nothing in the males.
It’s not just mice and rabbits in which the males lack any nipples, incidentally, but it is quite the rarity in mammals. Ever seen a stallion with nipples? No, you haven’t, because horses are also in the no-male-nipple club. So are marsupials. But what Nature takes with one hand, it gives with another – males of the Dayak fruit bat not only have nipples, they have lactating nipples. It really does seem to be an evolutionary lottery when it comes to the male nipple.
But remember the TL;DR version – male rabbits don’t have nipples. All the rest is interesting to varying degrees, but really, that’s everything you need to know.