How to recognize the signs of heat in dogs

The estrus period is the reproductive phase that the unneutered female dog has to go through. During this period, the eggs will ripen, making the dog fertile and pregnant with puppies. Due to the changing hormone levels in the body, the dog will show abnormalities in body and in behavior at this stage. These changes will help you distinguish whether the female dog is in the breeding season or not.

Table of Contents

Understanding estrus in dogs

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Understand the basic reproductive cycle in dogs. If you’re wondering if your dog is in heat, first you need to understand the female dog’s hormonal cycle. When the female dog reaches the time of ovulation, the body is ready to reproduce, the high estrogen levels then promote the release of the egg from the ovary. If mating takes place during this time, the egg is fertilized and an embryo is formed. ^{[1] X Trusted Source American Society for the Prevention of Cruelty to Animals Go to source}

Bitches usually enter estrus during puberty, about 6-24 months old depending on breed. Small dogs often come into heat earlier than large dogs.

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Know when it’s time to check estrus. Dogs typically go into heat twice a year, with an average interval of six months, depending on breed. ^{[2] X Research Source}

This information can help you judge whether your dog is in heat. For example, if the female dog was in heat a month ago, the current behavior may indicate an abnormality.
Although most dogs are in heat twice (ie every six months) a year, in some hormone-related cases bitches may be in heat more than usual. Some bitches go through estrus every six months like clockwork, while others have a higher frequency. An estrous cycle of 4 to 8 months is still considered normal.
Dogs are usually in heat for a period of three to four weeks.

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Know the signs of heat. The estrus period is itself a pattern, and the dog’s vulva will swell and bleed for the first week. However, Nature has a mysterious arrangement of Man, because between 7-14 days, the bleeding can stop or decrease. This leaves owners recklessly thinking that the mating season is over and their dog is no longer at risk of becoming pregnant. But, that was a fatal mistake! The middle of the week is the time of ovulation and the time with the highest pregnancy rate.

Midweek is also the time when your dog is most interested in finding a boyfriend, if you don’t want your dog to get pregnant, this is the time to tighten up.
Between day 14 and day 21 of estrus, menstruation may return, but will gradually decrease and stop completely. However, the vulva will usually stay larger than normal for the next few weeks (although the dog can’t get pregnant now because the estrous phase has ended).

Observe the female dog’s physical and behavioral signs during estrus

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Observe if the dog’s vulva is swollen. The vulva is located just below the anus. In the pre-estrus stage, your dog’s vulva will begin to swell slightly. When it comes to estrus, the dog’s vulva will be three times larger than normal and reddish in color. ^{[3] X Research Sources}

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Watch for signs of vaginal bleeding. Vaginal bleeding is a sign that your dog will soon enter heat. When the dog enters the estrus phase, the amount of blood will decrease quite a lot and the blood will gradually turn brownish.

For a dog that is extremely clean and licks away the blood that is eliminated by the body, it will be difficult for the owner to know if he is menstruating or not. A helpful tip is to line the dog’s bed with a white cloth or towel. That way, when he sleeps, the dog will bleed out the white pad.
If you plan to breed a dog, record the date the bitch started bleeding. Breeding is best done on the 10th or 11th day (from the first day the dog bleeds) and every other day for the next three days.

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Notice if the dog is constantly licking himself. Another sign that your dog is entering estrus, or pre-estrus phase, is repeatedly licking the vulva. Although some other bitches don’t, most will develop this behavior around the time they enter estrus.

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Note if your dog starts behaving unusually. Dogs in the pre-estrus stage often exhibit different behaviors than usual. Specifically, bitches in the pre-estrus stage are often stressed, sensitive, and excitable. ^{[4] X Research Sources}

Some puppies will bark more or become more aggressive towards other people or dogs nearby.

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Note the increase in pairing behaviors. A female dog is likely to be in heat if she starts riding on a male or other dog. This is one of the signs that the dog is completely under the influence of heat. Dogs can even ride on your legs.

However, the fact that dogs ride on other dogs or human legs does not always indicate that they are in heat, sometimes it can be caused by behavioral problems, such as masturbation, desire. dominating or acting strangely submissive.

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Observe the change in the dog’s tail position. When bitches enter estrus, their tails will curl to the side to facilitate mating. This behavior is very common in bitches during estrus and is known as “flapping the flag”. ^{[5] X Research Sources}

You can also discover this behavior by vigorously scratching your dog’s butt. If the dog’s paw suddenly becomes stiff and the tail swings to the side, it is waving a flag.
Never insert anything into a dog’s vulva or vagina to check if it is ready. You will accidentally damage the red sensitive tissues in this area and cause pain to your dog.

Notice the behavior of male dogs

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Know that some bitches can be in “hidden heat”. These dogs did not show any noticeable signs of heat. They do produce sex hormones but do not develop the usual additional signs, such as vulvar swelling.

The only way to really confirm a female dog in estrus is to observe the male-female dog interaction and ask questions. Male dogs will detect a change in the female dog’s sex hormone levels, although a small change can still stimulate the male dog’s interest and interest.
Note that some dogs may “skip” estrus. If your dog has been feeling unwell recently, is in below-average health, or has lost weight, his body will store energy and won’t enter estrus as expected. This is nature’s way of showing that a bitch’s body needs all of its energy reserves as the primary goal is to be in top condition to be able to take care of the puppy.

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Pay attention to the level of aggression in male dogs. If you have several male dogs with a female dog that is likely to be in heat, observe how one male dog is aggressive towards another male dog. When more than one male dog is near a female dog in heat, the males will begin to behave more aggressively towards each other to show who is dominant and to mate with the female.

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Observe an increase in verbal communication behavior and arousal. If you have two dogs, one male and one female, in the breeding season, be aware of how the male dog reacts when not around the female dog. If the male looks more anxious than usual and whines when he’s not around the female dog, it could be a sign of arousal. This is a good sign that your dog is in the breeding season.

Although this is not simple because you need to analyze based on the normal physical and behavioral changes of the male dog in the context when he is not near his “wife”. Some dogs often show anxiety when separated from their partners and this is difficult to distinguish from a sexual crisis.

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Observe the interaction between males and females. If you let your male dog roam around the house, watch what happens when he’s around the female dog. If the female allows the male to lick and sniff her vulva for a long time, the female dog may be in heat. Specifically, if the female dog lets the male dog ride, it is a sign that “she” is in heat. ^{[6] X Research Sources}

However, allowing another dog to ride is also a sign of submissive behavior, so again, you need to do a thorough analysis and ask questions, such as whether Is it heat or not, how does your dog normally behave around other dogs? Remember that sniffing each other’s backs is something dogs do a lot at the best of times, just to recognize each other!
If your pair doesn’t interact often, hold the male on a leash and lead him close to the female. One or both of them may be aggressive if they are not familiar with each other.

Check the estrus period at the veterinary clinic

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Ask your veterinarian for a blood test to determine if your dog is in heat. ^{[7] X Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test in detecting canine plasma progesterone concentrations. Manothaiudom, Johnston, Hegstad. JAAHA 31 (1) 57-64} A test can be used to measure the level of progesterone in the blood, if this hormone is high, the dog is entering estrus. It’s very simple, the doctor only needs to draw a blood sample of the dog and send it to the laboratory. Low progesterone levels indicate that the dog is not currently in a cycle, medium levels indicate that the dog is in heat, and high levels indicate that the dog is pregnant.

Another alternative is the test used in research facilities. This method measures the amount of Luteinizing hormone (LH) in the blood stream, which is elevated before ovulation. However, this is not a test that is commercially available as a test kit.

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Ask your veterinarian to do a Vaginal Cytpogy (cervical smear) test. This is also a quick and easy check to do. ^{[8] X Research Source Reproduction in the dog and cat. Christiansen. Publisher: Bailliere-Tindal.} The doctor will use a swab with a cotton tip to rotate it around the wet lining of the vulva and then spread the tip of the cotton ball on the microscope slide. After drying, the smear is stained and examined under a microscope.

Specimens consisting of many large keratinocytes accompanied by red blood cells are a typical sign of estrus. Combining this with physical signs is enough to confirm whether a dog is in heat.

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Ask yourself if the symptoms you see indicate heat or indicate a health problem in your dog. This means that your common sense plays a very important role in determining whether a dog is in heat. If in doubt, take your dog to the vet. ^{[9] X Small Animal Internal Medicine Research Source . Nelson & Couto. Publisher: Mosby}

Is the dog about to go into heat? If yes, this is more likely a sign of heat than a symptom of illness.
Did the dog just go into heat? If that’s the case then a new period won’t come so soon and this could be another health problem.
Is the dog mentally healthy, eating normally and acting as usual? If everything is fine, it’s possible that the symptom is due to estrus.
Is the dog different from usual, anorexia, drinking a lot of water or vomiting? If so, an urgent health issue may be going on and the dog needs to be seen by a veterinarian.

Advice

If you find out that your dog is sexually active and you don’t want him to get pregnant, after the heat period is over, take the dog to the vet and have it spayed.
You can tell when estrus ends by the same observation method. When the estrus period ends, the dog will not allow the male dog to ride, the vagina dries and his vulva returns to its normal size.

Warning

If your bitch has been spayed but has blood coming out of her body as a sign of heat, take her to the vet right away. Dogs can develop urinary tract infections, venereal diseases such as Transmissible Venereal Tumor (TVT), scratches, trauma, or infections of the uterus.

Steps