As a breeder, you already know that the dog’s reproductive cycle is unique. Ovulation timing in dogs can be complex and involves tracking the rise and fall of three hormones:
- estrogen,
- luteinizing hormone (LH), and
- progesterone.
Your female dog will have specific days in which she is the most fertile. And it’s up to you to pinpoint when these occur to yield the best breeding results.
Sound complicated? Don’t worry, we have all the information about the timing of ovulation in dogs you need, right here at Breeding Business!
Ovulation Timing in Dogs
Generally speaking, most bitches are the most fertile at nine to eleven days of their estrus cycle. However, for the best results, many breeders will mate their dogs five and six days after the bitch’s luteinizing hormone surge. Her progesterone levels should also rise from basal levels to over 5 ng/ml. This indicates that ovulation is imminent. If her progesterone levels don’t rise, it suggests that the LH surge was due to hormonal fluctuation and not due to ovulation.
If you artificially inseminate your bitch, it’s best to wait a couple of days after the ovulation to begin. While fresh sperm can live long enough to wait for the egg to mature, chilled or frozen semen has a shorter lifespan and can die before the egg is fully mature.
Hormones Involved in Ovulation Timing in Dogs
Many hormones work together to start ovulation. Three of these hormones are commonly monitored throughout estrus. These are estrogen, luteinizing hormone, and progesterone. Follicle-stimulating hormone (FSH) and gonadotropin-releasing hormone (GnRH) also take part. Although general estimates are possible without testing for these hormones, some dogs will begin their heat days early or days late.
Estrogen
Estrogen is a primary sex hormone. In dogs, four types of estrogen occur naturally. These are estrone (E1), estradiol (E2), estriol (E3) and estetrol (E4), the latter of which only arises during pregnancy. When synthesized, estrogens are responsible for the regulation of the female reproductive system and secondary sex characteristics. Estrogens increase uterine growth, stimulate endometrial growth, and promote sexual receptivity, to name a few specific functions. But what role does estrogen play in ovulation?
Proestrus begins with external signs of estrogen increase. Your dog develops vulval swelling and pinkish-white discharge. This phase averages nine days. Once estradiol (E2) reaches a high concentration, a surge of luteinizing hormone (LH) begins. This, in turn, initiates ovulation. Your bitch releases more than one egg during ovulation. The exact number varies depending on her size, age, breed, and health. The number of eggs that are fertilized depends on the timing of the breeding and viability of the sperm.
Luteinizing Hormone
Luteinizing hormone (LH) is a hormone that acts alongside follicle-stimulating hormone (FSH) and has a close relationship with estrogen. In female dogs, LH triggers estradiol (E2) production in the ovaries by supporting structures known as theca folliculi. Eventually, once these follicles are completely mature, 17α-hydroxyprogesterone (a relative of progesterone) inhibits further estrogen production and stimulates the release of LH. This phenomenon is known as an “LH surge.” Detecting this surge of LH indicates impending ovulation in your bitch.
Your bitch can be tested for LH levels in her blood during her estrus cycle. Testing should be done alongside progesterone testing for the most accurate results. This helps to confirm if the LH surge was due to ovulation. The bitch’s fertile period falls between four to seven days after the LH surge, with the most fertile days being five and six.
Dogs with either high or low levels of LH may experience infertility because the hormone directly impacts the dog’s reproductive system. This can limit the ovulation process.
Progesterone
Progesterone (P4) is a naturally occurring steroid hormone. It helps with pregnancy, embryogenesis, and the estrus cycle. Estrogens upregulate or induce the expression of progesterone, amplifying its effects. In the reproductive system, progesterone helps to prepare the endometrium for implantation. It affects the vaginal epithelium, making it thicker and harder for sperm to penetrate. Progesterone even decreases the maternal immune response so that the body accepts the pregnancy. But what roles does it play during ovulation?
The levels of this hormone are low during the pre-ovulatory phase of estrus, rising quickly after ovulation and elevating during the luteal phase. Once progesterone blood levels reach 5-8ng/mL, ovulation can begin. As well as this, progesterone increases your dog’s core temperature during ovulation. Because progesterone levels rise so significantly during ovulation, a vet can pinpoint ovulation by testing for this hormone.
How to Tell That Your Dog is Ovulating
Ovulation timing in dogs can be a complex process. To get the most accurate timing, some breeders test their bitches for luteinizing hormone and progesterone.
You may also ask your vet to carry out a vaginoscopy to check for physical changes in your bitch. A vaginal cytology examination can also reveal changes in your bitch’s vaginal cells and assess her fertility.
LH Levels
A luteinizing hormone test provides an accurate and semi-quantitive measure of your bitch’s reproductive status. This is because a surge of LH triggers ovulation, typically 2 days after the surge. The eggs require two to three more days to mature and live for four to seven days thereafter. Thus, the bitch’s fertile period falls between four to seven days after the LH surge, with the most fertile days being five and six.
For the most accurate LH testing, daily serum samples are drawn beginning from the fourth or fifth day of proestrus. If LH testing is done during estrus, the LH surge may have already occurred and cannot be identified. In addition, a progesterone test should also be done to identify the baseline progesterone level. Once an LH surge is seen through testing, daily serum samples should also be taken to test for progesterone levels. If the LH increase was the actual pre-ovulatory surge, the levels of progesterone should rise within three days and stay high. If progesterone fails to rise, it indicates that a proestrus fluctuation in your bitch’s LH was seen, not the true LH surge.
Progesterone Levels
A progesterone blood test is the most accurate method for timing dog breedings. The results of the test are reported numerically, as ng/dl, and are obtainable within 24 to 72 hours. If your vet has the facilities to test in-house, you can get results within hours. Ask your vet about their progesterone testing facilities to avoid disappointment.
In the beginning of your dog’s cycle, progesterone levels are relatively low at less than 2ng/ml. This is the baseline. To determine your dog’s baseline, their first progesterone level is measurable on days 5 to 6 of their cycle. As your bitch enters estrus, progesterone levels rise above 2ng/ml. During this increase, continue to draw serum samples for testing roughly every other day. Your vet may suggest going two days between tests if progesterone levels are very low.
Once the progesterone levels rise above 5-8 ng/ml, most vets will recommend natural breedings to be done as soon as possible. Although the eggs are not yet mature at 5 ng/ml, fresh semen can survive long enough in the bitch’s reproductive tract. For chilled semen breedings, shipments can be arranged once progesterone levels rise above 20 ng/ml. Frozen semen breedings are postponed until the progesterone levels are 35 ng/ml or higher.
Vaginoscopy
Vaginoscopy involves the use of a scope to visualize the vagina of a bitch. Your bitch’s vaginal mucosa will change dramatically in color and texture during the different phases of estrus. These changes are caused by estrogens, but later changes are due to progesterone. Vaginoscopic examination during anestrus will show the vaginal mucosa as pink and smooth. The only fold present at this time is the dorsomedial fold, which has been present since your dog’s embryological development. Its pink color comes from the capillaries, which are close to the vaginal mucosa during this stage.
During proestrus, vaginoscopic examination shows longitudinal folds throughout the vagina. Its mucosa becomes a paler light pink than before. In late proestrus, transverse folds form on top of the longitudinal folds. The mucosa becomes paler too. With estrus, the mucosa is very wrinkly and pale. The mucosa is also very sensitive and will respond to the touch of the vaginoscope with hyperemia. During estrus, your bitch will ovulate and consequently becomes fertile.
Vaginal Cytology
Vaginal cytology involves microscopic examination of cells in the vaginal epithelium. Tracking changes in the morphology of these cells provides a means of assaying changes in your bitch’s estrogen levels. To prepare a smear, a swab is inserted several inches past the vulva by a vet. Once the swab is inserted, it is rotated two or three times to pick up enough cells. The tip of the swab is rolled across a glass microscope slide.
Proestrus brings several distinct changes. Intermediate and parabasal cells are predominant. By proestrus, capillary breakages occur, causing leakages of red blood cells through the uterine epithelium. An examination from early to later proestrus shows a gradual shift from intermediate cells to superficial cells.
Neutrophils are also present as well as large numbers of bacteria. By the time estrus sets in, a vaginal smear will show a predominance of superficial cells. Most bitches also undergo full cornification. If the bitch breeds within a day of preparing the vaginal smear, sperm are likely to be seen amongst the epithelial cells. When diestrus comes around, the superficial cells decline and intermediate cells are predominant.
How to Assess Ovulation Timing for Breeding
Your bitch’s hormones fluctuate during her estrus cycle. These fluctuations dictate which days are the best for breeding her to a stud. To get a better understanding of ovulation timing in dogs, let’s take a look at the hormones and how they impact your bitch’s most fertile days.
Hormone Changes
By following your bitch’s hormonal changes you can pinpoint the precise day that she ovulates. This means that you can identify when her best breeding times are. These measurements are especially important for artificial insemination.
The most accurate way to follow your bitch’s hormonal changes is through progesterone testing. You will need to test your bitch at the first noticeable signs of heat for the most accuracy. This will give a baseline level of progesterone for you to work from. At this stage, her progesterone levels should measure <1.0 ng/ml. About four days later it’s advisable to measure progesterone every other day.
Your bitch’s LH surge only lasts for 12 to 24 hours, so it can be easily missed if LH is the only hormone you’re following. Ovulation occurs about 48 hours after this point. For this reason, most vets will test for progesterone as well as LH. Progesterone changes can also confirm the surge of LH. Occasionally, fluctuations can occur in LH without ovulation following soon after, so it’s best to check to be sure. Once progesterone exceeds 5 ng/ml, ovulation can occur at any time. The consequent LH surge initiates ovulation and eggs emerge two days thereafter, on average. Eggs are viable for three to four days after they implant in the uterus.
The Right Days
Breeding your bitch on days three and five or four and six after the LH surge ensures the best conception rate. If only one breeding is possible, it’s best to do it on day five or six after the LH surge. But why is this the case? After the LH surge, your bitch’s progesterone levels will increase rapidly within three days, coming above 5 ng/ml when tested. It’s at this stage that ovulation occurs. Breeding your bitch a few days after the LH surge ensures that you breed your bitch when her egg is mature.
Dog Ovulation Calculator
There are no ovulation calculators made specifically for dogs. This is because ovulation timing can easily be missed in dogs. As well as this, one bitch can have a different cycle pattern than another bitch. Consequently, there is not a reliable online resource for timing your bitch’s ovulation. However, there are pregnancy calculators and calenders that may be of use to some breeders. Examples of such calculators are accessible at Pet Sci and Emergency Vets USA.
As a general rule, your dog’s pregnancy should last 63 days. A pregnancy calculator shows the expected due dates, including the earliest and latest dates. It’s important to note that these dates are only estimates and that dates can vary.
Ovulation Timing in Dogs – FAQ
Have any more questions about ovulation timing in dogs? Feel free to refer to our Frequently Asked Questions section for more details. If in doubt, always ask your vet for advice.
Ovulation in dogs lasts for 48 hours after an LH surge, meaning that ovulation should last for two days. After the egg implants in the endometrium, it spends two to three days maturing. Once the egg is mature, it lives for four to seven days thereafter.
The process begins with a peak of estrogen levels. This peak, by positive feedback, causes a surge of LH and follicle-stimulating hormone (FSH). This hormonal change lasts for 12 to 36 hours and results in the rupture of the ovarian follicles. Due to the rupture, the egg releases from the ovary. The egg then moves through the fallopian tube towards the uterus. A further 60 hours are necessary for the egg to fully mature. The egg then remains fertile for about 48 hours.
To accurately determine when your dog is ovulating, progesterone and LH testing should be done by a vet. Starting from the fourth or fifth day of proestrus, LH and progesterone levels are measurable to identify a baseline. From here, you can accurately tell how much your bitch’s hormones have increased over the next few days. Once an LH surge is seen in a sample, daily serum samples should be taken to test for progesterone to confirm the surge. If progesterone does not rise, it’s possible that the surge of LH was due to a proestrus hormone fluctuation rather than a true LH surge. If the LH surge is true, ovulation should occur within 48 hours.
On the day of the LH surge, your bitch’s behavior might change. The change is often abrupt and occurs on the day of the LH surge, or right around it. Your bitch might show more flagging behavior and can appear more restless. Generally speaking, when your bitch starts flagging, she is ready to breed two to three days later. In order to pinpoint the precise time of ovulation, it’s best to run progesterone and LH tests to be sure.
A progesterone blood level of 5ng/ml indicates ovulation in dogs. To illustrate the significance of this measurement, your bitch’s progesterone levels are negligible before ovulation, resting at <1.0 ng/ml on average. About four days later, it’s best to test your bitch’s progesterone every other day to look for an increase.
Your vet might also test for LH at the same time to identify a surge. Once your bitch’s progesterone levels exceed 5ng/ml and an LH increase occurs, it’s highly likely that ovulation is imminent. Your bitch should ovulate within 48 hours after the LH surge.
There are only a few successful methods of inducing oestrus in dogs. With current research, oestrus can be induced using dopamine agonists and gonadotrophin-releasing hormone (GnRH) agonists. Prerequisites for success using these methods include sexual maturity, good reproductive health, and enough of an interval from the previous oestrus. These treatments should only be given by a qualified vet due to the risk of side effects and suppression of the oestrus cycle if done incorrectly.
Dopamine agonists can shorten the duration of anestrus and induce oestrus sooner. Two oral formulations are used, including cabergoline (5 μg kg−1 day−1) and bromocriptine at an increasing dose until proestrus begins. The duration of this treatment lasts anywhere from eight to 40 days. Its effectiveness is not sufficiently evaluated yet. However, pregnancy rates of 70 to 100 percent have been noted after dopamine agonist treatments. Side effects are sometimes seen after this treatment. These include vomiting and even a change of coat color after shedding.
Similar to the dopamine agonist treatment, deslorelin implants are given during anestrus. At present, the deslorelin implant is the only GnRH agonist authorized for use in veterinary medicine. One such implant is the Ovuplant®, which contains 2.1mg deslorelin. Its primary effect is to increase FSH and LH in the bitch, leading to oestrus induction in >90 percent of treated dogs. Clinical signs of ovulation should arise within one week after the implantation. Like the dopamine agonist treatment, pregnancy rates are variable with an overall rate of 60 percent. The implant must be removed from all bitches after ovulation is detected. Due to this, the implant is typically placed subcutaneously in an easy-to-access area. If not removed in time, a pregnant bitch might experience luteal insufficiency. In non-pregnant bitches, there may be a prolonged suppression of the estrus cycle.
In order to conceive, your dogs should mate a total of two or three times. Most breeders will allow two matings and might go for three if the bitch previously has not conceived. The two or three matings are normally done 24 or 48 hours apart. This is because mating twice in one day can reduce the stud’s sperm quality, therefore reducing fertility rates and overall success. It’s also not plausible for some breeders to travel more than twice to meet the stud if the stud lives far from the bitch. Check these details with the owner of the stud when you make your initial inquiries to avoid disappointment and confusion.
If artificial insemination with chilled semen is done, the same rule applies. However, the timing of the insemination might vary. Some breeders will wait until progesterone levels reach over 20 ng/ml to inseminate with chilled semen. This is your bitch’s most fertile period. As well as this, chilled semen has a shorter lifespan than fresh semen, so it’s important that it reaches the mature egg in time.
Generally speaking, most bitches are the most fertile at nine to eleven days of estrus. However, to be more precise, your bitch’s most fertile period is between five and six days after her LH surge. At this time your bitch’s progesterone levels are high at over 20 ng/ml.
It’s important that you don’t breed based on high progesterone alone – your bitch’s progesterone levels will continue to rise, regardless of whether she is pregnant or not. Her progesterone levels can rise as high as 40 to 50 ng/ml, or even up to 90 ng/ml, depending on the individual. Elevated progesterone simply indicates that your bitch can support a pregnancy, and do not suggest that she is carrying.
Ovulation timing in dogs involves careful and precise testing for three hormones: estrogen, luteinizing hormone, and progesterone. Although general estimates can be given without testing, some dogs will come into heat days early or days late, so the most fertile periods can easily be missed. To avoid disappointment, be sure to ask your vet about their testing facilities!