When Is the First Heat for a Jack Russell Terrier Puppy

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Knowing about the heat cycle of your Jack Russell will help you prepare adequately for when the time comes. The information will help you make an informed choice on whether you want to breed it at that time or you will wait until another time. So, when is the first heat for a Jack Russell terrier puppy?

When Is the First Heat for a Jack Russell Terrier Puppy?

The first heat for a Jack Russell terrier is between six to nine months old and usually lasts around 21 days. Its level of estrogen increases and then decreases before the ovaries release eggs. You can expect two heat cycles in a year.

Graphic image of a Jack Russell Terrier puppy and a text stating that their first heat usually happens around 6-9 months old

During the heat cycle, you can expect your Jack to bleed for approximately 7 to 10 days out of the 21. During the rest of the days of the cycle, it should not have any vaginal discharge or blood. If you notice the bleeding has gone on for more than 10 days, you should take it to the vet for an evaluation.

Signs That Your Jack Russell Terrier Is in Heat

When your JRT is in heat, you will likely observe the following signs.

Swollen Vulva

This is one of the most obvious signs of your Jack being in heat. Your dog will also be licking its genital parts more than usual. The swollen vulva and the bloody discharge are causing it to lick itself. While the dog usually keeps itself clean during this time, you may want to get dog wipes or a heat diaper, so it does not make a mess.

Change in Urination Schedule

It may be challenging to know when exactly your Jack urinates; you only have to clean the litter box. However, when your dog is on heat, you will realize you are cleaning it more often than usual. You are likely to realize that:

  • It is peeing a lot
  • The urination is more frequent among male dogs
  • It raises its leg differently, especially when around the male dogs

When it is in heat, its urine contains pheromones and hormones that attract male dogs. You will also find her marking objects in the home or during walks to get the attention of the males.

An image of a Jack Russell terrier sitting

Mounting and Humping

When it is ready to mate, a female Jack will mount, thrust or hump. It will do this to other female and male dogs or anything resembling a dog, including a stuffed animal. Do not be surprised when it also tries to mount your legs.

Aggression and Anxiety

When your dog starts showing signs of anxiety and aggression, she is on heat. At first, you may be unable to link the aggression to being in heat; you will probably think it needs to be socialized. However, when you notice the other signs, you will be able to link them to be in it.

You are also likely to notice other emotions such as being more affectionate, at ease, lazy, or signs of distress. All the signs differ for individual Jacks, although most tend to display anxiety and aggression.

How to Take Care of Your Jack Russell When Its on Heat

You can take care of your dog when she is in heat by:

  • Consult a vet considering it is your dog’s first time and you do not know what to expect.
  • Avoid letting it go to the yard unsupervised as it may meet a male dog and become pregnant.
  • Ensure it gets enough exercise and rest.
  • Ensure that it stays clean during the whole period it is on heat; you can use doggie diapers.
  • Keep it groomed; you can do this by trimming the fur around its genitals. This will also make it easy for you to clean that area.
An image of a woman embracing her dog

Related Questions

Other similar questions you may have about your JRT being in heat are answered below.

How Often Do Jacks Go Into Heat?

Jack Russells go into heat approximately every six months. If you do not spay it, it will be able to go into heat twice a year until it is around eight to ten years old. Spaying before its goes into the first heat cycle helps prevent it from getting breast or ovarian cancer.

Is It Possible for My Jack to Go Into Heat and Not Bleed?

Yes, it is possible for your Jack to go into heat and not bleed. This is called a silent heat cycle. While bleeding may not occur, other signs may be present such as a swollen vulva.  You can consult your vet if this happens so they make sure your furry friend is doing okay.


Knowing about your dog’s heat cycle helps you be prepared. You know what to expect, and if you are looking to have puppies, you can set it up to breed with an appropriate male. If you are not, you can take extra care to ensure that it does not get pregnant during this period.