When a female dog doesn’t show signs of a heat cycle (estrus), the reason may be ovarian hypoplasia, a condition in which the dog’s ovaries do not develop normally, but remain in their immature state. These small ovaries cannot secrete enough of the hormones estrogen and progesterone to support a heat cycle. As a result, the female dog shows no interest in mating with a male, and does not get pregnant if artificially inseminated.

Ovarian hypoplasia is a hereditary abnormality of the female ovary, and is also referred to as ovarian dysgenesis. It’s the most common congenital abnormality of the ovary in dogs.

The signs and symptoms of ovarian hypoplasia in female dogs all relate to reproduction. They include:

While dogs who are presumed to be in heat may be artificially inseminated, no fertilization takes place and the uterine wall does not prepare for the nourishment of a fetus.

Heredity is the sole cause of ovarian hypoplasia. An abnormality in the dog’s chromosomes occurs during the initial formation of a fetus. There is no reported connection between a particular breed and the incidence of ovarian hypoplasia. 

Before arriving at a diagnosis of ovarian hypoplasia, a veterinarian will perform an examination. They may need to run several tests to rule out other possible causes of infertility, such as malnutrition, hypothyroidism, ovarian or vaginal tumors, anemia or other blood disorder, and underproduction of estrogen and progesterone. Lab tests include checking thyroid hormone level, estrogen and progesterone levels, and a complete blood count and a metabolic (chemical) panel. Vaginal infection or tumors can be ruled out with cultures and microscopic examination. If none of these tests are positive, ovarian hypoplasia may be considered.

Imaging to visualize the dog’s pelvis may include X-ray, ultrasound, or MRI. A diagnosis of ovarian hypoplasia can be supported by imaging, which shows an undersized ovary in a dog more than two years old. This is the typical maximum time frame for a female dog to come into heat for the first time. 

Genetic testing, called karyotyping, may be done to demonstrate the presence of a chromosome abnormality indicating ovarian dysgenesis. Karyotyping is performed on blood or bone marrow, which are put into special tubes and allowed to grow. After time, cells are removed and stained for examination under a microscope. The resulting chromosome array can identify abnormalities such as misshapen chromosomes, or the presence of chromosomes associated with ovarian hypoplasia. 

There is no treatment that will reverse or cure ovarian hypoplasia. Hormone therapy will do nothing to encourage ovarian growth. In order to prevent later ovarian tumors or other reproductive disorders, a veterinarian will recommend having the dog spayed. 

The spay procedure removes a female dog’s ovaries and uterus, along with the birth canal “horns” in which fetuses are nurtured until birth. While it is an invasive procedure with a possibility of complications, spaying is one of the simpler and most commonly performed surgeries. It carries very little risk to the dog. Rare complications may include bleeding, sensitivity to anesthesia, or infection.

The spay procedure is typically performed in less than an hour, after which the pup is observed in the recovery area of the clinic. IV pain medications may be administered. Once the dog is fully awake and there are no signs of immediate side effects, they are released. Overnight stays in the clinic are common.

Once your dog returns home, you can help them recover as comfortably and timely as possible by limiting their activity to protect the incision and allow the dog to regain strength. Check the incision twice a day, and watch for discharge, including blood. Keep the incision dry, and report any other complications such as fever, pale gums, unsteady gait, significantly reduced food and water intake, labored breathing, or vomiting and diarrhea to your vet immediately. Monitor your dog’s pain levels and administer medications as needed, and continue to feed them a regular diet.

At least one followup appointment will be necessary for the vet to check the incision and assess the dog’s overall health. After that, routine annual visits will be resumed. Female dogs who are spayed are expected to recover completely within a few weeks. 

Long-term, the female dog will live a long and healthy life barring any unexpected diseases in systems other than the reproductive organs. 

Infertility can be expensive to treat. If you suspect your dog is at risk of developing infertility, start searching for pet insurance today. Wag! Wellness lets pet parents compare insurance plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!

Average vet care costs: $200 - $900