In the film Meet the Parents, Greg has an awkward conversation with his fiancée's father. Due to some confusion, Greg has to cover it up by saying he milked a cat.
(Long story) When Jack (the father) shows skepticism, Greg says that he can milk anything with nipples. Jack responds “I have nipples, Greg. Could you milk me?”
Well, male mammals often do have nipples (cats being no exception) but they tend to be vestigial.
So, do male cats have nipples? That is the question to be answered here.
How Nipples Work
During mating season, male and female cats mingle with each other and the female gets pregnant. When a mother cat nurses, her kittens' suckling stimulates nerve endings in the nipple.
This tells the pituitary gland to release the hormones prolactin and oxytocin. The prolactin takes nutrients from her blood supply to turn them into milk. This is why she seems hungrier than usual.
Oxytocin makes cells around the nipple contract and force milk down.
Mama cat needs to be left alone when this is happening. Not only is it easier for her to feed her babies when she's calm, but mother cats can get a bit hissy and scratchy when she's got babies to protect.
Do male cats have nipples?
The answer is yes, though they may be small and undefined. Many male animals have vestigial nipples that serve little to no purpose. In the South, there's a quaint saying “About as useful as tits on a boar hog!” to mean that something is not at all useful.
The defining characteristic of any creature in the class Mammalia is the young developing in the womb and the mother producing milk to feed her young. However, there are some mammals that don't have nipples.
The platypus and the echidna for example are of an order known as Monotremes. Though they lay eggs, they do produce milk for their young through milk patches.
Cats, however, are placental mammals just like horses, dogs, pigs and humans. Their young form in the mother's womb and she feeds them her milk until they're ready for solids.
Why do male cats have nipples?
It is surmised that the nipples are formed in the womb of mammals long before the sex is determined. This explains why males have nipples, even though there is really no purpose for them. At first, a male fetus is indistinguishable from a female fetus. After a while, the DNA triggers the sex hormones that cause trait development.
The testosterone in a male kitten fetus halts further development of the mammary gland, leaving behind something much like the coccyx bone on the human pelvis.
If nipples were resource-consuming, male DNA would most probably have evolved to stop them from developing in order to conserve the resources that otherwise would have been spent on something that is, on the whole, completely useless.
As it is, nipples are allowed to develop as there simply is not much of an advantage in the extra complication of stopping them from developing. Basically, Mother Nature has decided not to fix what isn't broken.
How many nipples do cats have?
The British sci-fi comedy Red Dwarf features a character known only as Cat due to being a humanoid life form (designated as Felix sapiens) that evolved from cats the way humans evolved from apes. At one point, after being told that the cruiser they’re getting a distress call from has a crew of beautiful women, Cat says “I'm so excited all six of my nipples are tingling!”
Fortunately, we never do see Cat's bare chest to verify this. (Cat would never be caught underdressed on any occasion.)
As for cats in reality, there is no defined number for how many nipples they can have. Cats will almost always have an even amount of nipples. However, cats have been known to have an odd amount as well. (Interestingly, this is a rare occurrence in humans that was once thought to be a sign of witchcraft.)
Pertaining to the exact number, cats can have as little as four, but as many as ten! On average, the number is six including tom cats. (Shh! Don't tell Cat he's average in anything!) Some kittens born in the same litter may have different numbers. Gender doesn’t alter the number. It's all a matter of genetics.
Finding His Nipples
When you look for a cat’s nipples, you will find them on the belly. Unlike with humans, their nipples can be found in more or less even rows near the pelvis. Due to the fur, it may be difficult to find all of them.
However, two can be found among the fine fur lining on the lower belly. On males and females that are not currently pregnant or nursing, they will look more like pimples than anything.
Do Cats Leak Milk? Is It Normal?
Just as with pregnant human women, pregnant cats may start to leak milk. This is really very common and normal. You might see her licking it off. If so, do not worry because this is perfectly fine. She probably just doesn’t like her fur getting wet. Leaking nipples does not necessarily mean that giving birth is imminent for your little queen.
Milk leakage can happen anytime throughout the pregnancy though it is most apt to happen the closer to labor she is.
Determining Gender
As gender has nothing to do with nipples, this is not a sure way to determine gender. When you want to determine the gender of a kitten, the easiest method to use is a visual check. Hold the kitten still under the belly and lift up the tail. If you have a female cat (known as a queen), the urinary tract opening and rectum will be very close together.
You might be able to see the vulva, which will be a vertical slit just beneath the rectal opening. If you have a male cat (known as a tom), the rectum and urinary tract openings are a bit further apart plus there is a small scrotum in the middle.
The male cat’s penis forms right below the scrotum but cannot be seen easily as it is covered in what is called the prepuce.
Conclusion
It is true. Male cats have nipples, though they have no practical use for them. If you feel a few tiny bumps on your cat's underside, it is probably just a nipple and nothing to worry about.
Any change in color, size or sensitivity, however is a cause for concern that may need to be checked by a veterinarian.
If your cat is female, the most likely reason for change in nipples is pregnancy. Rarely, if ever, will anything of notice happen to a tom's nipples.