Jack Russell Terrier Puppy: How to Define the Sex

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The Jack Russell Terrier is a small dog that gives birth to tiny puppies. The size of a puppy’s genitals of this breed is extremely small during pregnancy. That’s why vets can’t determine the sex of a puppy with an ultrasound.

However, it can be easily determined once the puppy is born. In this article, I’ll discuss how to define the sex of a Jack Russell Terrier puppy.

How to Define the Sex of a Jack Russell Terrier Puppy

It’s important to know how to define the sex of a puppy to take care of the newborn whelp properly. Plus, it’ll also help you choose the gender you want if you’re planning to become a pet owner.

Graphic image of two white and brown Jack Russell puppies that explains how to easily find out the sex of Jack Russell Terriers

The following are two quick and easy methods to determine the gender of a JRT puppy.

Look for Male Sex Organs

The easiest and quickest way for sexing a newborn Jack Russell is to look for its male genitals. Pick up the puppy gently and lay it in your cupped hands on its back, especially if it’s a newborn. Keep in mind that puppies are born deaf and handling them in the wrong way can make them nervous.

  1. Inspect the center of the puppy’s belly for the belly button. You want to look for a dark pink spot located right below the rib cage where the belly fur ends.
  2. The small dark pink spot is the pup’s belly button. It may still have the umbilical cord attached to it if the puppy is a few days old. But it will automatically fall off within a few days.
  3. After locating the belly button, you’ll need to inspect the pink area of the belly without hair. If you see another small raised spot about an inch below the belly button, the whelp’s gender is male. This raised spot is where the puppy’s penis will develop.
A tri-colored Jack Russell terrier dog with black and brown colored eyes is lying on a gray floor

If you don’t see anything below the belly button and the patch without hair is plain and smooth, you have a female puppy. The outline of this spot will be dark pink but its raised part will have a baby pink color.

It’s important to note that male puppies also have testicles but it’s not easy to see them in newborn Terriers. However, you can spot them if your puppy is a few weeks old (about six to eight). They’ll be enclosed in the scrotum located on the lower side of the whelp’s rear legs. The size of each testicle will be around one to three centimeters.

Important Note: You don’t want to touch any of these parts of the puppy as they’re extremely delicate.

Look for Female Sex Organ

You can also determine the sex of your young JRT by inspecting its rear end. You’ll need to use the same technique to place it in your hands. Then, use one of your fingers to move the pup’s tail slightly.

It’ll allow you to see the puppy’s anus located under the tail. Here you’ll see a small fleshy, raised, and leaf-shaped area, called the vulva, with dark pink color, if the gender is female. In the upside-down position of the pup, it’ll be right above the anus and it’ll also have a small vertical slit. If you don’t see anything like that near the pup’s anus, then the gender is male.

Important Note: Both female and male Terriers have nipples on their belly, just like all other mammals including humans. So, they won’t help you in determining the puppy’s gender.

Can Urination Habits Help You Sexing a Jack Russell Terrier Puppy?

If you’re a dog owner, you’d already know that male and female dogs of all breeds have different urination habits. Male dogs lift one of their rear legs and the female dogs squat while urinating. So, can it help you define the sex of your young JRT?

Unfortunately, it’s not possible because both sexes of puppies in this and other breeds squat while urinating. That’s because the rear legs of male pups aren’t strong enough after whelping for several weeks.

A tri-colored Jack Russell terrier dog is lying on a gray blanket in a well-lit room

They start lifting their legs while urinating after four months and it becomes their habit after six to eight months. It is also best to train the JRT puppies how to potty train at that age.

When Can You Define the Gender of a Newborn Jack Russell Terrier Puppy?

You can define the gender of a newborn JRT right after it’s born. You only need to look at the genitals of the pup to find out the sex. However, the difficult part would be handling the newborn puppy right after birth, as they’re delicate.

So, it’s wise to wait for a day or two and check when the puppy is cleaner and feeling comfortable. It’ll also provide the newborn with time to further develop its genitals and you’ll be able to see them easily.

Tips for Sexing a Jack Russell Terrier Puppy

The following are some important tips that you need to keep in mind while defining the sex of a JRT puppy.

  • Never try to pick up a young JRT, or any other pup, with its tail.
  • Place the back of the pup on your hands and cover as much body area as possible. You can also use a towel placed on a soft cushion to rest the puppy on its back.
  • Don’t pick up newborns frequently during the first month after birth. Not only can it be dangerous for the whelp, but it can also upset the mother and make it aggressive.
  • Don’t touch the young ones if their mother is feeling uncomfortable.
  • If a whelp becomes distressed, nervous, or fussy, place it with its mother immediately.
  • Newborn puppies must never be handled or kept away from their mother for more than five minutes. Otherwise, they’ll get cold as they can’t regulate their normal body temperature on their own.
  • Handling dogs too much can make them sick by getting cold, and it can result in rejected puppies.
  • Never touch the genitals of puppies while defining their sex. You can accidentally damage them as they’re extremely fragile.
A woman with curly hair wearing a white button-down shirt holds a brown and white coated Jack Russell in a backyard

Frequently Asked Questions

Here’s a list of the most commonly asked questions about defining the sex of a JRT puppy.

Why Does Defining the Jack Russell Terrier Puppy Sex Matter?

Knowing how to define the Jack Russell Terrier puppy’s sex helps you pet a dog with the gender you want. It also comes in handy when you already have a dog and don’t want to introduce another whose gender may cause complications.

Do All Jack Russell Terriers Have Nipples?

Yes, just like other mammals, all Jack Russell Terriers have nipples on their belly. So, this feature can’t help you define the sex of a newborn pup. The female dog nipples enlarge and remodel and the ducts of male dog breasts shrink as they reach puberty.

Can the Puppy’s Size Help You Determine the Gender?

No, the size of the puppy can’t help you determine its gender. While it’s true that male dogs are slightly bigger than females, the size difference is negligible at the time of birth. All newborn JRTs look similar and super tiny.

Final Words

The best way to define the gender of a JRT puppy is to examine its belly. Male puppies will have two raised spots, one for the belly and the other for the penis. Whereas female puppies will only have the belly button.

You can also examine the rear end of the puppy right under the tails to examine the female genital organ. Here, a female pup will have two points, anus, and vulva, and the male will have only one (anus). Make sure that you place the pup with its mother right after defining the sex.