Heat Cycle Abnormalities in Dogs

Updated: March 15, 2024

Female dogs can have heat cycle issues and they can happen when you least expect it. These heat cycle abnormalities in dogs can be an irregular heat cycle in dogs or main dysfunctions occurring in a dog's heat cycle.

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"Abnormal cycling can lead to infertility in female dogs."

A Dog's Heat Cycle

Your dog will have her first heat cycle by the time she reaches puberty. On an average, your dog will reach puberty when she's six months old but this actually differs from one breed to another. Smaller dog breeds go into heat earlier compared to bigger breeds. Bigger breeds may not come into their first heat until they're eighteen months to two years old. But a dog’s heat cycle may also depend on other things, like a dog’s health condition and lifestyle.

How Often Will Your Dog Go Into Heat?

Dogs usually go into heat once every six months or twice every year, but this will differ from one breed to another (as mentioned above). Small breeds, like a Yorkshire Terrier can go thrice a year. Meanwhile a German Shepherd heat cycle will differ from them as large breeds may only go into heat once a year.

A typical dog’s heat cycle goes on as follows:

Stage 1: Proestrus

There is vaginal discharge, males become attracted to females but the females still don’t have interest in mating and may become aggressive when mounted. Length: 4-20 days.

Stage 2: Estrus

Your dog will have a swollen vulva, together with some bloody vaginal discharge; mating occurs during this phase with your female dog giving in freely to the males. This is the stage most suitable for breeding, where your dog is most fertile. Length: 5-13 days.

Keep in mind that it is not always appropriate to breed your dog, even if she is in this stage. For example, you should not be breeding your female dog in her first heat. For more information on why breeding a female dog in her first heat is not OK, check out this article.

During this stage we recommend using female dog diapers for heat cycles. Pet Parents® Washable Dog Diapers will keep your pup and house clean from any messes during this heat cycle stage. These diapers will allow you to keep your female dog in heat comfortable on beds, furniture, or around the house without the risk of stains.

Stage 3: Metestrus (or Diestrus)

This is the period where your fur-baby is no longer receptive to males and where your fur-baby's hormones begin to go back to their normal levels. Length: 60-90 days.

However, if your dog is pregnant, pregnancy will last between 60-64 days.

Stage 4 Anestrus

This is the period of inactivity in dogs (sexual and hormonal) between estrus phases. Length: 2-4 months.

To learn more about how long your dog's heat cycle may last, check out this article.

What if your dog is not coming into heat?

When your female dog goes through a heat cycle, this is where she becomes receptive to a male for the possibility of mating, breeding, and eventually pregnancy. Sometimes you may wonder why your dog has not yet come into heat. But actually, you may not realize that your dog has already cycled because she never exhibited the normal signs of a heat cycle like:

  • Swelling of the vulva
  • Sudden change of mood
  • Sudden change of behavior like peeing and pooping in areas she knows she shouldn't
  • Bloody discharge from the vulva
  • Receptive to male dogs who are nearby

The following are some of the situations that are possibly causing this abnormality in your dog's heat cycle.

Heat cycle abnormalities in dogs

Once your fur-baby begins her heat cycle, she should experience estrus at regular intervals, according to VCA Hospitals. Most female dogs have their heat cycle every four to ten months, although in some dogs there are exceptions; in other cases, some dogs may only cycle once per year.

Abnormal heat cycle in dogs is a term used to describe a female dog that is not experiencing normal heat cycles. These abnormalities may include delayed, absent, or irregular cycles.

Heat cycle abnormalities in dogs include the following:

Absent heat. Your dog missed a heat.

Silent Heat. Your dog goes through an undetectable heat cycle where you're not able to tell she's in heat because no visible heat signs are exhibited. It is important to remember that male dogs can still detect a female dog in silent heat and will still be open for mating.

Prolonged Heat. A heat lasting longer than the average heat cycle.

Split Heat. A heat that suddenly stops and then continues after some weeks.

Shortened Inter estrus Interval. Too short of an interval between heat cycles.

Prolonged Inter estrus Interval. Too long of an interval between heat cycles.

Premature Ovarian Failure. Your dog's ovarian functions weaken or stop at an early age.

Primary persistent anestrus. This is when a female dog that has reached 24 months of age still haven’t reached estrous cycling. According to VCA Hospitals, this condition may be caused by a number of reasons, like malnutrition, excessive physical activity, medicines that meddles with fertility, or a lack of exposure to other females experiencing heat. Additionally, hormonal imbalances and genetic problems may also cause abnormal estrous cycles.

Additionally, if your fur-baby has gone through one cycle but does not cycle again, secondary persistent anestrus may be diagnosed. This heat cycle abnormality is a delay of over 18 months since the last estrus. In some dogs, this is an age-related condition; dogs under 24 months old may experience irregular cycles, and the same is typically seen in older dogs.

These abnormalities are a cause of concern for most pet parents because abnormal cycling can lead to infertility in female dogs. Also, if no pregnancy takes place for a number of heat cycles, the uterine lining begins to thicken until cysts are formed. The thickened lining then secretes fluids which is a very suitable environment for bacterial to grow and develop.

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Causes and proper management

The treatment for heat cycle abnormalities in dogs can vary. Your veterinarian will rule out the possible causes of these and some of the possible causes can be:

  • Hypothyroidism
  • Ovarian Hypoplasia - where your dog's ovaries do not fully reach sexual maturity resulting to not being able to produce the right amount of estrogen needed by the body
  • Ovarian Tumors
  • Malnutrition
  • Improper nutrition, etc.

Treatment can include hormonal medications through supplements and possible surgery for tumors and pyometra. You can use Pet Parents® Washable Dog Diapers as a way to cover up the incision site for your dog to prevent her from licking, scratching the area. Progesterone measurements and vaginal cytology are also needed to determine whether your female dog is cycling or not.

You may also provide your fur-baby additional nutrients by giving them Multifunctional SoftSupps®. These multivitamins will help give your fur-baby achieve optimum health and will help strengthen their overall wellness and nutrition. These can be especially helpful if there is an imbalance in the dog’s nutrition, but are also beneficial for your dog’s general health.

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"These [Multifunctional SoftSupps®] will help give your fur-baby optimum health and will help strengthen their overall wellness and nutrition."

Moving forward with dog heat cycle abnormalities

Abnormal heat cycles in dogs are more common than you think. But remember, there are always solutions regardless of the type of heat cycle abnormality your female dog is going through. Heat cycle abnormalities can be determined with the help of your vet so that you can provide the proper care for your fur-baby. Chances are, there are a few things you can do at home to help!