How to Tell If Your Dog Is in Heat — And What to Do about It

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Learn the signs of a dog in heat.

One aspect of dog ownership that new and experienced owners alike may overlook is estrus, also known as heat. All female dogs that aren’t spayed go into heat. Recognizing the signs that your dog is about to go into heat, as well as signs your dog has actually entered the phase, will help you get through heat with as few surprises as possible

What Does It Mean If My Dog Is in Heat?

When female dogs go into heat, they’re entering estrus, the stage in their reproductive cycle when they can become pregnant. Depending on the size of your dog, heat can begin when they’re anywhere from 6 to 24 months old. In general, the smaller the dog, the sooner they go into heat. 

A dog’s first heat cycle normally lasts between 3 and 4 weeks. After a dog has entered heat for the first time, it then occurs every 4 to 8 months, or about twice a year. Some dogs enter heat in a consistent time frame, while others’ cycles may vary; neither is usually a sign of larger health concerns. If your dog starts to show signs of entering heat a month or two after just going through heat, however, it could be a sign of a health issue that your vet should check out. 

4 Signs Your Dog Is Going into Heat

The most frequent symptoms before heat include:

1. Swollen Vulva

Located just below the anus, your dog’s vulva will turn redder in color and increase in size — often 2 to 3 times its normal size. 

2. Behavior Quirks

A dog entering heat can become more skittish or aggressive around others, including people and animals but especially other dogs.

3. Increased Licking of the Vaginal Area

While almost all dogs occasionally lick themselves in this area, you may see it much more frequently before they go into heat.

4. Vaginal Bleeding

If you notice bloodstains near or around areas where your dog rests, it’s likely your dog is in proestrus and the heat phase is about to begin. Dogs may bleed for up to 10 days during this phase.


4 Signs Your Dog Is in Heat

Once your dog is in heat, you may notice physical and behavioral changes, and changes in how other dogs behave around her. Here are the most frequent signs your dog is in heat.

1. Decrease in Vaginal Bleeding

The amount of blood typically decreases when your dog is in peak heat. Once this occurs, your dog is in the most fertile stage of estrus for about a week to 10 days, until bleeding starts again (although bleeding doesn’t always recur). 

2. Mating Behavior

When your dog is around other dogs (both male and female), her behavior will be noticeably different. This may include mounting other dogs or letting herself be mounted. If no other dogs are around, your dog might try to mount your legs. 

3. Switched Tail Position

Once she is fully in heat, your dog’s tail will often move or curl to the side. This is known as flagging and lets male dogs know she is ready and available for mating. 

4. Male Dogs React Differently

If you have male dogs in your household or come across one on a walk, they’ll react differently to your dog in heat. This could include aggression toward other male dogs or increased barking and whining. They may also show much greater interest in your dog’s genital area.

Keep in mind the signs of going into heat and being in heat vary from dog to dog; your dog may not show all (or any) of the above symptoms. If your dog doesn’t show any signs of heat but did show signs of entering heat, she is still likely in heat.

How to Care for Your Dog While She’s in Heat

If you don’t want your dog to have puppies, there are some steps you should take to minimize the chances. 

1. Avoid off-leash walks or taking trips to the dog park.

A dog in heat may cause aggression among male dogs and could result in fighting (even if the dogs are neutered). It’s best to avoid this altogether by skipping trips to the dog park or off-leash activities until your dog no longer shows signs of being in heat. 

2. Get doggie diapers. 

Dog diapers can absorb any bloody discharge and are the easiest way to guarantee your dog won’t get pregnant while she’s in heat.

3. Keep your dog indoors.

Even if your yard is fenced in, the scent of a dog in heat can cause male dogs to go the extra mile to try and mate with her. Dogs may even find a way into a fenced yard, so keeping your pet indoors is the best precaution. 

4. Give your dog extra attention. 

If your dog isn’t able to do her normal outside activities, she will likely get frustrated. Be sure to give her extra petting/grooming and maybe even a new toy to help keep her occupied.  


Consider Getting Your Dog Spayed 

Spaying your dog can reduce her chances of mammary cancer and a uterus infection called pyometra. In addition to eliminating the possibility of accidental pregnancy, getting your dog fixed may be the easiest way to reduce your stress level and help her lead a healthier, longer life. 

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