Not Coming Into Heat in Dogs

Written By hannah hollinger
Published: 05/01/2017Updated: 04/28/2021
Veterinary reviewed by Michele K.
Why is my dog not coming into heat?

What is Not Coming Into Heat?

Female dogs have heat cycles, or estrus. During this time, the female is receptive to a male and has the ability to reproduce. There are some times when your female dog, or bitch, has an abnormal heat such as a silent or split heat or does not come into heat at all. If your female does not come into heat for over 10 months, there is a possibiliy that her reproductive cycle is being suppressed.

Sometimes you may not realize that your female has actually cycled on time because she has had a silent heat. This is when your dog goes into heat but does not exhibit any of the normal signs of a regular heat cycle. Your female can still become pregnant during a silent heat. It is important to watch any intact male dogs closely; they will be able to detect a silent heat.

Possible causes of why your dog is not coming into heat include:

  • Silent heat cycle
  • Hypothyroidism
  • Ovarian hypoplasia 
  • Malnutrition
  • Tumor on the ovaries

Why Not Coming Into Heat Occurs in Dogs

Many times a female dog will not have a proper heat cycle until they are about two years of age. This is especially true in many large or giant breeds; they do not reach sexual maturity until they are two years old. You should be concerned if your female does not have a heat cycle by the time they are 24 to 30 months of age, and it would be a good idea to have your veterinarian examine her. 

Silent Heat Cycle

This occurs when your female will have a heat cycle without the normal symptoms such as bleeding and swelling of the vulva. Females will still be receptive to males and can become pregnant. Your veterinarian can check for a silent heat cycle by performing vaginal cytology and progesterone assays.


Your dog may be suffering from a thyroid problem that can cause irregular heat cycles and in more severe cases can cause your female to not cycle at all. Hypothyroidism is thought to be genetic and dogs diagnosed with it should not be bred.

Ovarian Hypoplasia 

There are instances when the ovaries do not fully develop and are incapable of producing enough estrogen for your female to come into heat or have a normal heat cycle. The mammary glands and the vulva will stay small and look underdeveloped. 


Female dogs that are malnourished from poor diet or recent illness will many times not have a heat cycle. Feeding a low quality dog food that is low in protein and fat content can cause your female to not have a heat cycle. If you are planning on breeding your female, be sure to feed her a high quality food to ensure that her body is able produce enough estrogen for a proper heat cycle.

Tumor on the Ovaries

Tumors can develop for many different reasons, some being cancerous and some being benign. When a tumor develops on your female’s ovaries, this can inhibit heat cycles. Your veterinarian will need perform diagnostic testing to determine if a tumor is present and whether or not it is cancerous.

What to do if your Dog is Not Coming Into Heat

Your veterinarian will need to conduct a full examination of your dog, and also run routine tests such as a biochemistry panel, complete blood count and urinalysis. If you suspect your dog is experiencing silent heat cycles, you will need your veterinarian to do weekly vaginal cytology and progesterone measurements to determine the exact days that your dog is in heat.  

Female dogs with ovarian hypoplasia will have elevated LH and an ultrasound will show if the reproductive organs are immature. Spaying a female dog that is diagnosed with ovarian hypoplasia is usually recommended. Blood testing will show if your dog is experiencing a thyroid problem.

It is recommended if your female dog is experiencing significant reproductive problems such as abnormal heat cycles or lack of heat cycles, she be spayed. Reproductive difficulties can be genetic and also can be indicative of a female dog who will be unable to properly carry or care for a litter.

Prevention of Not Coming Into Heat

While genetics can play a major role in your dog’s reproductive health, there are certain preventative measures that can be taken to give your dog a better chance of having a normal heat cycle. Feeding a quality dog food is one way to ensure that your female dog is not suffering from malnutrition. Do not feed a low quality food and avoid giving extra treats or table scraps.

Speak with your veterinarian about supplements that target the reproductive system of your dog. They may recommend a supplement that will keep your female cycling regularly. Regular checks by your veterinarian will hopefully catch any underlying problems such as hypothyroidism or tumors on the ovaries. If you are worried about your dog’s lack of heat cycle, be sure to have your veterinarian do a full assessment to figure out the cause.

Cost of Not Coming Into Heat

The treatments for this problem can range from very little cost, such as an office call to your veterinarian, to $7,000 depending on the exact cause. For example, hypothyroidism often averages at a cost of $600, while ovarian cancer is much more expensive, with treatments ranging to $6500. On average, treating a female dog that is not coming into heat can cost around $1300.

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Not Coming Into Heat Questions and Advice from Veterinary Professionals


American Pit Bull Terrier



One Year


130 found this helpful


130 found this helpful

My pet has the following symptoms:
No Heat Cycle
My dog turned 1 on July 29 and still hasn’t had her heat yet. I wanted to know if that was normal or should I go get her seen for it ?

Sept. 29, 2020

Answered by Jessica N. DVM

130 Recommendations

Hello- Thank you for your question. Most dogs go through their first heat cycle between nine and 12 months, but larger breed dogs may not go into heat until they are 12 to 18 months of age. If she doesn’t go into heat in the next few months it would be a good idea to schedule an exam with your veterinarian. At this time though I would just continue to monitor her.

Sept. 29, 2020

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1y 4m


46 found this helpful


46 found this helpful

My pet has the following symptoms:
My bitch is not coming into heat. She is 1year 4 months old. When she was about 2 months old she had an urinary infection which was treated by antibiotic. No issues since it was treated. I also gave her Mom. The moms first heat was at age of 1year. Should I start worrying about absent heat or is still too early? Thank you.

Sept. 27, 2020

Answered by Dr. Michele K. DVM

46 Recommendations

Thank you for your question. She is still young, and it can take some time for some dogs to come into heat. Each dog is an individual.

Oct. 13, 2020

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