How Long Do Fertilized Eggs Survive After Ovulation in Dogs?


Ovulation is the release of mature eggs from the ovaries in preparation for potential fertilization and pregnancy. In dogs, ovulation occurs during the estrus stage of the heat cycle, which is when the female is receptive to mating with males.

The typical canine estrus cycle lasts 18-21 days from the initial heat stage to the end of the estrus period. Ovulation happens around the 11th day of the cycle, but can range from 8-20 days depending on the individual dog. This corresponds with the peak fertility window when conception is most likely.

Once released, eggs have a short window of viability to be fertilized before they die off. If fertilization does not occur within 48-72 hours after ovulation, the eggs will no longer be viable ( Understanding the ovulation cycle and egg lifespan is key for breeders to optimize conception chances.

Signs of Ovulation in Dogs

a diagram showing the stages of a dog's estrus cycle including ovulation

There are several physical and behavioral signs that indicate a dog is ovulating during her heat cycle. According to the AKC, the most noticeable sign is vaginal bleeding. Prior to ovulation, the discharge will be bloody. But as estrogen levels drop and progesterone rises, the discharge becomes lighter, often pink or straw colored [1]. Swelling of the vulva also decreases as ovulation approaches.

Other physical signs include enlargement of the ovaries and increased sexual receptiveness. The dog may hold her tail to the side, which provides easier access for breeding. She may also lick or nip at the male during mating. The AKC notes that female dogs only allow mating during ovulation. At other times during the heat cycle, she may growl, snap or run away from males [1].

According to VCA Hospitals, most dogs ovulate around the 11th day of estrus. Ovulation lasts 1-2 days. The discharge becomes scant and the vulva returns to normal size shortly after ovulation ends [2].

When Does Ovulation Occur

Ovulation generally occurs around day 10-14 of the canine heat cycle, although the exact timing varies between individual dogs. According to the AKC, ovulation happens approximately 48 hours after the LH hormone surge, which marks the transition from the proestrus to estrus phase of the heat cycle (AKC). The LH surge causes the follicles containing the eggs to rupture and release the eggs for potential fertilization.

After the LH spike, the eggs are ovulated around 48 hours later and can be fertilized for the next 2 days as they travel through the oviducts. However, the eggs must mature for about 48 hours after ovulation before they can be successfully fertilized (Town Animal Hospital). Therefore, the optimum time for breeding is 2-5 days after the LH surge, when the eggs have ovulated and fully matured.

It’s important to track signs of the LH spike, such as changes in vaginal cells viewed under a microscope, to pinpoint when ovulation will occur. This allows breeders to time mating or artificial insemination appropriately. Testing hormone levels and using ovulation prediction kits can also help identify the LH spike and approximate ovulation timing.

Ovulation Tests

There are several types of tests available to help confirm when ovulation occurs in dogs:

a vet examining a urine ovulation test strip

Blood tests detect a rise in the hormone progesterone, which indicates ovulation. A vet can draw blood periodically to track progesterone levels [1].

Urine tests check for specific metabolites present when the dog ovulates. These include tests like the Witness Relaxin test, which detects rising levels of the hormone relaxin [2].

Vaginal cytology involves collecting cells from the vagina and examining them under a microscope around the suspected ovulation time. Changes in cell appearance signal ovulation [3].

breeders may use a combination of these methods to increase accuracy in pinpointing ovulation day.

Egg Lifespan and Viability

After ovulation occurs, a dog’s eggs only remain viable for fertilization for approximately 48 hours. This is according to veterinarians at the UC Davis School of Veterinary Medicine [1]. The eggs must be fertilized by sperm within this 48 hour window in order to conceive puppies.

Once an egg has been released from a dog’s ovaries, it begins to travel down the fallopian tubes toward the uterus. A dog’s eggs are only fertile and capable of being fertilized during this journey before they reach the uterus. If sperm from breeding does not penetrate the egg within about 48 hours after ovulation, the unfertilized eggs will eventually disintegrate and be reabsorbed into the body.

Knowing when a dog ovulates is important for breeding success, since the fertile window is so short. There are tests available to help identify the LH hormone surge that precedes ovulation by 24-48 hours [2]. This can pinpoint optimal days for breeding. However, due to the short viability, timing breeding too early or late by even 12 hours could result in missed opportunities for fertilization.

Conception Chances

The highest chances of conception occur in the peak fertility window for dogs, which is the 48 hours after ovulation. According to research, using intrauterine artificial insemination at 6, 7, 8 and 9 days post ovulation resulted in conception rates of 100%, 71.4%, 37.5% and 0% respectively. This indicates the sharply declining chances of conception even just a few days after ovulation has occurred.

a graph showing conception chances declining sharply after 48 hours post ovulation

Another study found that natural breeding fertile dogs once between 4 days before to 3 days after ovulation resulted in a 95% conception rate. The takeaway is that the fertile window spans about a week, but peaks in the 1-2 days after ovulation when conception chances are highest.

The average conception rate for a dog in heat bred during peak fertility is around 70-95%. However, rates can vary quite a bit from 8% on the low end up to 100% at the peak. Monitoring your dog’s cycle and identifying the ovulation date can help maximize chances of successful breeding.


Infertility and Egg Quality

There are several reasons why a dog’s eggs may have reduced viability leading to infertility. Age is a major factor, as egg quality declines as a female dog gets older. According to the VCA, fertility issues typically start around 6 years old for larger breeds and 7 years old for smaller breeds. The chances of conception decline rapidly after this point.

Timing is also critical. Eggs only survive for about 48 hours after ovulation, so there is a small fertility window. Missing this window, even by a few hours, can result in failed conception. Health conditions like hypothyroidism or progesterone deficiency can also impact ovulation timing and egg quality [1].

Other health issues in the female dog such as uterine disease, ovarian cysts, or anatomical defects can reduce fertility. Systemic diseases, nutritional deficiencies, and obesity may also play a role. Exposure to toxins or medications can damage egg quality as well. In some cases, there are no obvious causes for reduced egg viability.

It’s recommended to have breeding dogs tested for potential health conditions prior to mating. Monitoring the female’s cycle and optimal timing of breeding is also key. If conception issues persist, veterinary exams and testing can help determine if there are underlying causes impacting fertility that require treatment.

Breeding Considerations

The best time to breed a female dog is usually between days 10-14 of the heat cycle, which is when ovulation typically occurs. However, the exact timing can vary between breeds and individual dogs. Some key tips for optimal breeding timing based on ovulation include:

Monitor your dog’s behavior and look for signs of ovulation like swelling of the vulva and vaginal discharge. This usually happens around the peak fertility window. You can also use at-home ovulation test kits designed for dogs.

Have your vet confirm ovulation timing if possible, through tests like vaginal cytology and progesterone blood tests. This can pinpoint the 2-3 day fertile period.

For most dogs, the prime time to breed is days 10-14. But some ovulate earlier or later. Smaller dogs tend to ovulate sooner while larger breeds ovulate later.

Breed every 1-2 days during the suspected fertile period for the highest likelihood of conception. Don’t just breed once.

Track the heat cycles and log details to determine your dog’s ovulation patterns over time. This can help optimize future breeding timing.

If breeding for the first time, wait until at least the second heat cycle for the best results. Avoid early pregnancies in very young dogs.

Discuss any breeding difficulties with your vet, like failure to conceive after multiple tries. There may be health issues impacting fertility.

With close monitoring of ovulation signs and properly timed breeding, you can help ensure successful conception and a healthy pregnancy.

When to See a Vet

There are certain signs in female dogs that may indicate a reproductive issue that requires veterinary attention. These include:

  • Not going into heat by 1 year of age – Dogs typically go into their first heat cycle by 6-12 months of age. Failure to do so may signify an issue like ovarian hypoplasia or granulosa cell tumors.

  • Irregular heat cycles – The normal interval is 6-8 months. Cycles happening more frequently may indicate ovarian cysts, while less frequent ones could mean pituitary gland problems.

  • Prolonged heat cycles – Heat usually lasts 18-21 days. Excessively long cycles over 3 weeks could indicate ovarian cysts or uterine disease.

  • Abnormal discharge – Unusual vaginal discharge outside of heat, especially with a foul odor, may point to infection or uterine tumors.

  • Difficulty conceiving – Dogs not becoming pregnant after 2-3 cycles of breeding on appropriate days may have infertility issues requiring veterinary diagnosis.

  • Signs of pregnancy but no puppies – Symptoms like nesting, enlarged nipples or abdomen without eventual puppies may mean false pregnancy or pregnancy loss.

  • Abnormal cycles after having a litter – Unspayed dogs usually resume heat 6 months post-whelping. Quicker returns may signify retained placental tissue.

Schedule an appointment with your veterinarian if your dog shows any of these signs for a thorough examination and diagnosis. Timely treatment can help resolve many reproductive issues in dogs and restore fertility.


Here are the key points about ovulation timing and egg lifespan in dogs:

Ovulation generally occurs 2 days after the luteinizing hormone surge and release of eggs from the ovaries. This is when the eggs can be fertilized by sperm.

The fertile period and egg viability is short, around 24-48 hours after ovulation. After this time, the eggs will no longer be viable for fertilization.

There are behavioral and physical signs of ovulation in dogs, like receptive body posture, swollen vulva, and discharge. These usually last 5-10 days.

Ovulation tests and microscopic examination of cells can help pinpoint the exact ovulation time, which assists with breeding.

Egg quality declines as the dog ages, so fertility rates are highest around 2-5 years old. Health issues like hormone imbalances can also affect ovulation and conception.

Understanding the ovulation cycle and fertile window is important for optimizing breeding success in dogs. Consult a vet if you are concerned about any reproductive or fertility issues.

a happy dog breeder with a pregnant dog after optimal ovulation timing

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