ASK BARKPOST ANYTHING: ‘Why Do Male Dogs Have Nipples?’

As BarkPost writers and editors, we live, bark, and breathe dog stuff all day long. You could de-fur-nitely call us experts in the field. ASK BARKPOST ANYTHING is our weekly series where the BarkPost editors answer the serious, silly, and salacious questions from the world of dog! (And remember, if the answer helps you out, we accept payment in belly rubs.)

This week’s question was submitted by Mr. E. Smell*, who hails from Cary, North Carolina (*names have been changed):

Dear BarkPost: Why do male dogs have nipples? I just noticed my dog Ralph has a bunch of them, and it caught me by surprise. What’s up with him having nips? Thank you!

Interesting, I have wondered the same thing about male humans (among other questions I have for them). But before we delve any further into the glory of the man-nip, we here at BarkPost want to warn you that some of the images that follow may be considered NSFW (unless, of course, you work at BarkPost, in which case, this is totally normal…at least, I hope all the people who sit behind me feel that way). Let’s dive into dog nipples!

Your dog's nipples looked like this, right?
Your dog’s nipples looked like this, right?

The fact is, most mammals have nipples. Even cats, pigs and primates. Even Ralph. And even you, Mr. Smell. (But I’m sure you already knew about yours. And if you didn’t, congratulations! You got ’em, and they come in a nice set.)

mcconaughey use plz
They probably look like this guy’s.

Let’s begin with a quick overview of dog nipples. Like female dogs, male dogs have nipples, which extend in two rows from the chest into the groin area. Unlike female dogs, they do not possess a reproductive function, so they don’t generally secrete — and if they do, you should consult a vet, just to make sure everything’s okay. Nipple color and shape can change as a dog ages, so it’s normal for a dog’s nipples to be pink or black.

male dog nipple 1
An example of male dog nipples.

However, it’s not uncommon for dog owners to mistake a nipple for a tick — after all, pup parents are primed to worry whenever they see a dark bump on their dog. You can do a quick at-home test by looking closely at how the raised area is attached. If the entire bump is attached to the skin, it’s probably a nipple, mole, polyp, or scab, not a tick. On the other hand paw, if only one end of the bump is buried, it is likely a tick. And, if your dog’s nipple appears to have legs, then it’s most likely a tick, not a nipple with legs (although that would be cool). Of course, you can always consult your vet if you’re uncertain.

A nipple (l) and a tick (r). I couldn't find a picture of a nipple with legs, but you can imagine.
A nipple (l) and a tick (r). I couldn’t find a picture of a nipple with legs, but you can imagine.

The reason that male dogs possess nipples traces all the way back to their time in the womb. Whether a dog becomes a male or a female, all embryos begin as androgynous, so to speak. Nipples develop during the beginning stages in utero, before gender is determined.


Once gender is solidified, reproductive organs grow depending on the sex of the embryo, but those nipples are already in tow. (I guess nipples make me rhyme?)

dog embryo
A photo of a dog embryo, just a few days old. I can’t see the nipples yet, but they’re coming. Oh, they’re coming.

It’s most likely, then, that male dog nipples exist simply because they didn’t get weeded out by the process of natural selection. So, while it’s true that this trait doesn’t necessarily represent an evolutionary advantage for males, it also doesn’t have an evolutionary disadvantage, so male dog nipples were never selected against.

In short, male nipples appear to be purely decorative (but don’t get any ideas), as in, non-functional. This animal “nipple knowledge” is all good to know, both as a dog owner and when you’re in a stressful situation, like meeting your girlfriend’s parents for the first time.

If you want to Ask BarkPost Anything, send a message to [email protected]!

h/t A Vet’s Guide to Life & Life Science

Katie Kirnan

6 years ago

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