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How to Tell if a Dog Is in Heat: 9 Vet Approved Signs

Oliver Jones

By Oliver Jones

beagle on estrus cycle

Vet approved

Dr. Paola Cuevas Photo

Reviewed & Fact-Checked By

Dr. Paola Cuevas

MVZ (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Deciding to breed your dog is something that you should discuss with your vet. The question of whether to spay or neuter your pet is not always clear-cut. Researchers have identified links between desexing and an increased risk of health conditions, such as hip dysplasia and certain cancers.1 The chances vary with the breed.

The other thing to consider is weight gain.2 Some dogs become overweight or obese following the surgery due to hormonal changes. It’s safe to say that you should re-evaluate your pet’s diet based on the advice of your veterinarian. On the other hand, pregnancy also poses risks, especially for smaller dogs. You should only breed your female if she’s in tip-top shape.

After all, she must support the lives of the puppies for the approximate 63 days of gestation. If you’ve just bought a female pup and you’re uncertain about her status, several telltale signs can let you know for sure how to take care of your dog for the next few weeks. Below, we discuss how to tell if a dog is in heat.

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The 9 Signs Your Dog Is in Heat

1. Behavioral Changes

sad french bulldog
Image Credit: Mylene2401, Pixabay

Often, one of the first things that you’ll notice is your dog is acting strangely. She may seem more agitated or nervous. Your pup may even snap at you. Hormonal changes are driving her behavior. These chemicals can have far-reaching effects. Your once happy-go-lucky pooch may get moodier during this time.

2. Excessive Licking

Another telltale sign of a dog in heat or estrus is if she excessively licks her genital area. Hormones are the culprit, causing changes in your pup’s body both externally and internally. Some pets are more obsessive about this behavior than others.

3. Vulva Swelling

One physical sign of estrus is vulva swelling. If your dog is long-haired, you may not see it. However, this structure will get larger and might look reddish. That can also explain the excessive licking.

4. Vaginal Discharge

jack russell in heat
Image Credit: Reshetnikov art, Shutterstock

A female dog in estrus will have bloody discharge coming from her vagina. Estrus lasts 1 to 2 weeks. You might consider confining your pet during this time to keep your house clean and prevent an unwanted pregnancy. The discharge will eventually clear up and turn watery. That’s when your dog is most fertile.

5. Increased Urination

Your dog may want to go out more often during estrus to urinate. Swelling of your pup’s genitals will put added pressure on her bladder, prompting your pet to go outside more than usual. Once it’s resolved, your dog will return to her regular routine.

6. Inappropriate Mounting

You may find your pet mounting anything she can find. Remember that your pooch is acting instinctively. Don’t scold her for behaving this way.

Image Credit: John Danow, Shutterstock

7. Changes in Appetite

Appetite changes are common when female dogs are in heat. Some pets may feel uncomfortable during this time. That could affect your dog’s diet. For a while, she may ignore the canned food that she usually devours. However, we suggest keeping an eye on your pup for any other symptoms, such as GI distress or lethargy, which may mean that something else is going on instead.

Less often, females in heat might also appear hungrier than usual.

8. Tail Position

You may see your dog holding her tail to the side, up, or in other odd positions. Part of the reason is the vulva swelling. It’s also an instinctive behavior to indicate that she’s ready to mate.

9. Receptive Behavior

As your pup gets closer to her fertile time, she will start acting receptive to other dogs. The tail position is part of the courtship ritual signaling to males that she is fertile. At this point, she will allow male dogs to mount her.

Dog sniffing dog in heat
Image Credit: atiger, Shutterstock

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Final Thoughts

We hope this guide helps you understand how to tell if a dog is in heat! If you choose not to spay your pet, it’s essential to know the telltale signs of estrus. It can help you understand your pup’s change in behavior. It will also alert you to keep a closer watch on your dog. It’s worth mentioning that over 6 million unwanted pets go into shelters annually. We strongly urge you to confine your pooch to avoid adding to these numbers.

Featured Image Credit: Sigma_S, Shutterstock

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