Not Coming Into Heat in Dogs

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 strong chance 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

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 until they are 24 to 30 months of age you will want your veterinarian to 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.

Hypothyroidism

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. Ovarian hypoplasia is a result of abnormalities of the sex chromosome. 

Malnutrition

Female dogs that are malnourished from poor diet or recent illness will many times not have a heat cycle. Feeding a commercial 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.

Your veterinarian will need to conduct a full examination of your female and also run routine tests such as biochemistry panel, complete blood count and urinalysis. If you suspect your female 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 female is in heat.  

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

There are some instances where your veterinarian can induce a heat cycle by using human chorionic gonadotropin (hCG) or follicle-stimulating hormones (FSH). Your veterinarian will need to closely monitor your female while undergoing these reproductive therapies.

It is recommended if your female 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 who will be unable to properly carry or care for a litter.

While genetics can play a major role in your female’s reproductive health, there are certain preventative measures that can be taken to give your female a better chance of having a normal heat cycle. Feeding a quality food that is high in protein and fat is one way to ensure that your female 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 female. 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 female’s lack of heat cycle, be sure to have your veterinarian do a full assessment to figure out the cause.