How to Know if a Dog is in Heat – Signs and Symptoms

How to know if a dog is in heat? When do signs appear and how often do they return? How long do they last? How to cope with it? What is silent heat? How to determine when the dog is ovulating? All the answers are here!

Understanding the Course of Heat and the Dog's Sexual Cycle

Heat in female dogs corresponds to the periods of proestrus and estrus within the female's sexual cycle. They last on average 3 weeks.

This cycle includes the following four successive phases:

Appearance of the first heat in the dog

The dog's sexual cycle and the appearance of her first heat occur around her 10 to 12 months on average. In small breed dogs and in the German Shepherd, they are generally earlier and can appear as early as 5 to 6 months. Conversely, in dogs of giant breeds, the first heat may not appear until around 24 months.

The first heat is usually very discreet and can even go completely unnoticed by the owner of the dog. This is what we call the “silent heat”.

Duration of heat in the dog

A female dog generally has her heat twice a year, with 6 month intervals between each heat on average.

However, the interval between two periods of heat – called interestrus – can be longer or shorter depending on:

Remember, however, that it is above all the regularity of the anestrus phase (“sexual rest”) between two periods of heat that is important in a dog more than the rate at which your dog is supposed to have her heat. If a dog who had regular heat starts having it more and more distant or, on the contrary, closer, it is advisable to consult a veterinarian without delay. This change in rhythm can indeed reflect an ovarian problem.

How to Know if a Dog is in Heat

The heat period is accompanied by physical signs and a change in your dog's behavior.

During heat, you may notice a change in behavior in your female dog. The latter can become very cuddly or even a bit sticky or, on the contrary, become more aggressive. Other female dogs are generally poorly accepted while the company of males is rather sought after during estrus, even if it means running away from your home to find one!

Apart from behavioral changes, it is the physical and physiological signs that will tell you if your dog is in heat.

During the first phase of heat called proestrus, the dog's vulva increases in size and vulvar blood loss appears. These blood losses are more or less important depending on the dogs. The female emits sex pheromones in her urine and vaginal secretions which are recognized by males and attract them. However, the female dog still refuses mating during this phase.

During the second period of heat during which ovulation takes place (called estrus), the vulva becomes even more swollen, and the vulvar discharge decreases and clears up to sometimes stop completely. The female dog also places her tail on the side when a dog sniffs her hindquarters. It is during this period that the female accepts the mating and that she is likely to be impregnated by a male. The acceptance of the male lasts more or less long according to the females, from a few hours to more than a week for some of them.

Summary: How to tell if my female dog is in heat

Phase of the bitch's sexual cycle	Average duration	Hormonal variations	Visible physical signs	Behavioral changes
Proestrus	5 to 20 days	~ Rising estrogen ~ Near-zero progesterone	~ Vulva very swollen and turgid ~ Vulvar blood discharge	~ Male attraction ~ Refusal of mating
Estrus = ovulation	3-10 days	~ LH surge the 1st day of estrus ~ Decreased estrogen and increased progesterone	~ Vulva less swollen ~ Clearer to no vulvar discharge	Male attraction and mating acceptance
Metestrus or diestrus	57 to 65 days	High progesterone (hormonal impregnation) and drops at the end of the phase	~ Gestation or not ~ At the end of this period: start or possibly lactation of pseudopregnancy	Male refusal
Anestrus	2 to 9 months	Estrogens and progesterones secreted in small quantities	No discharge and normal size vulva (reproductive system at rest)	None

Abnormal Heat in the Bitch

In some bitches, the heat does not follow the usual pattern described above. We refer to this as abnormal heat.

Among these abnormal heat, we can observe:

The “silent” heat

We speak of “silent” heat in the bitch when the clinical signs of heat are very discreet or even nonexistent: no or little vulvar discharge, no swelling of the vulva, and no attraction to males.

These silent heats usually occur during the bitch's first heat or in bitches over 10 years old. Some small breed bitches can also present this type of atypical heat.

It is not that the heat of the bitch goes unnoticed or that the bitch does not ovulate for all that.

Split heat

At first, bitches normally enter a period of heat: they show vulvar blood loss for 3 to 10 days, attract males and sometimes even accept mating. Then, the heat stops suddenly without ovulation occurring. After a few days or weeks, normal heat (accompanied by ovulation) resumes. Most often, it is young bitches under 2 years of age who experience this phenomenon of split heat which has no effect on their fertility.

Prolonged heat

Prolonged heat is very long or even continuous heat in the bitch, one that is too long compared to the breed’s average. They often reflect the presence of an ovarian cyst or a problem of hyperestrogenism and are most often found in older bitches. The occurrence of this prolonged heat justifies a consultation with the veterinarian.

How to Deal with a Bitch in Heat

If you do not want your dog to have a litter then it will be necessary to take some precautions throughout her heat:

You will also need to resort to the use of hygienic protections for your dog so that she does not soil your interior when she loses blood. There are protective dog panties in which you can add sanitary napkins or disposable dog diapers. Even though blood loss is usually minimal, it can still stain textiles very heavily.

It is preferable to accustom your dog gradually and positively to the wearing of these protections and well before these heat periods so that she accepts them more easily the day when she will need them.

• How to Calm a Male Dog When a Female is in Heat

How to Tell When Your Bitch is Ovulating

If you want your bitch to have pups, it may be useful to determine precisely the time of her ovulation, in other words, the ideal time for mating in order to maximize the chances of procreation. This is all the more useful if the owners of the breeding male need to travel several hundred kilometers to mate or if the bitch has already been mated several times without results.

To do this, the veterinarian can perform vaginal smears and a hormonal dosage of progesterone. In practice, it suffices to bring your dog to the veterinarian 5 to 6 days after the start of her heat to begin the follow-up by carrying out a vaginal smear. Depending on the observation of the cells present on the smear, the veterinarian will be able to determine whether the bitch is rather at the beginning of proestrus or at the end of proestrus.

If the bitch is at the onset of proestrus, her ovulation will not happen right away! On the other hand, if it is at the end of the phase, the veterinarian will take a blood test to determine the progesterone. It is this dosage that will determine whether or not the bitch is ovulating.

Medically monitoring your dog's heat may require you 3 to 4 visits to the vet, but it is the most accurate way to determine the moment of ovulation.

Obviously, it is also possible – in a more empirical way – to base oneself on the observation of the bitch and her behavior. Thus, the decrease in vulvar discharge and their clearing up are signs that shortly precede ovulation.

Male acceptance is an unreliable criterion because it can occur up to two days before ovulation. It is also not systematic in all bitches in heat because bitches do not always accept the males that we have chosen for them. Some bitches with a strong temperament or particularly fearful may refuse the mating while they are in the estrus phase.