Dog Progesterone Levels Chart for Breeding Timing

Assuming both dogs are healthy, a mistimed breeding is the most common reason a female doesn't get pregnant, according to veterinarians writing for the American Kennel Club. The fix is a simple blood test repeated every few days during her heat. This guide turns those results into something you can use: a canine progesterone levels chart you can read at a glance, the math for converting lab units, a step-by-step testing plan, and the warning signs that mean you should call your vet before the stud ever arrives.

Progesterone in dogs behaves differently than in most mammals. In many species it rises only after the egg is released. In a female dog, the follicles start producing it before ovulation, so the level begins creeping up while she is still in heat. Researchers at the Virginia-Maryland College of Veterinary Medicine describe this early rise as unique to the species, and it is exactly what makes testing useful: the progesterone dogs produce before ovulation lets a vet see the event coming instead of guessing after the fact.

The actual trigger for ovulation is luteinizing hormone, or LH. It peaks for a short time and is released in pulses, so catching it takes daily blood draws. Progesterone climbs steadily instead, which is why most breeders track it every couple of days and use it to work backward to the LH surge and forward to ovulation.

Outward signs only take you so far. Swelling, discharge color and a female's willingness to stand all shift during heat, but they vary a lot from dog to dog. Dr. Emmanuel Fontaine, a reproduction specialist writing for the AKC, describes females that ovulated as early as six days into their cycle and others that ovulated 30 days in. No calendar rule covers that range. A blood test does.

Typical progesterone levels dogs show at each stage of heat are listed below. The ranges come from IDEXX's interpretation guide for its in-clinic analyzer, cross-checked against published veterinary research. Treat this dog progesterone level chart as a map of the sequence, not a rulebook, because your vet will read your results against the specific lab or machine that produced them.

Table 1. Dog progesterone levels chart by heat stage (ng/mL)

Once ovulation passes, the numbers keep rising for weeks. The Virginia-Maryland researchers note that peak levels later in the cycle can land anywhere between 15 and 80 ng/mL. That's why a single high reading can't tell you much on its own. What matters is where it sits in the series of tests that came before it.

Labs report progesterone dog levels in one of two units: nanograms per milliliter (ng/mL) or nanomoles per liter (nmol/L). The same result looks about three times larger in nmol/L, which is how breeders end up worrying over a 15 that is actually a normal ovulation reading. Michigan State University's Veterinary Diagnostic Laboratory, which reports in nmol/L, gives the conversion: multiply ng/mL by 3.18 to get nmol/L, or divide nmol/L by 3.18 to get ng/mL.

Table 2. Converting progesterone levels in dogs between units

Units are only half the story. Analyzers aren't identical either. Dr. Fontaine points out that a reading of 5 to 6 ng/mL on one machine might show up as 4 to 5, or 8 to 10, on another. Your vet's interpretation is tuned to the equipment they use, so run every test in a series through the same lab or in-clinic analyzer, ideally with blood drawn at the same time of day.

It's the question every breeder asks, and the honest answer surprises people. What should a dog progesterone level be to breed depends on when she ovulated, not on a target value. Dr. Fontaine explains that when fertility is at its best, progesterone might read around 10, around 30, or even above 60 ng/mL, so no single figure marks the perfect moment. The test tells you when ovulation happened. Your breeding dates count forward from there.

The reason is biology. Canine eggs are released immature and need about two days before they can be fertilized. Sperm survival then decides how early you can breed. Fresh semen lives for several days inside the female, so natural matings have some room for error. According to Dr. Jane Barber, a board-certified theriogenologist, chilled sperm survive roughly one to three days once inseminated and frozen-thawed sperm only about half a day on average, which is why frozen breedings demand the tightest timing of all.

Table 3. Typical breeding timing by semen type

If you're working with a stud owner, share the plan early. Our guide to the questions to ask a stud dog owner before breeding covers shipping, timing and what happens if she doesn't take, and you can read why breeding windows on Petsfindly are strict on purpose.

Most reproduction vets want a first sample within the first week or so of heat, counting day 1 as the first day you notice swelling or bloody discharge. Advice varies slightly. Dr. Fontaine suggests about day 6, Iowa State University's theriogenology service recommends 5 to 7 days after the first signs, and other AKC contributors suggest 7 to 10 days. The goal of progesterone testing for dog breeding at this stage is a baseline, so you can see the climb the moment it starts.

After that, the number sets the pace. A low result usually means you can wait three to five days. Once the level starts to rise, most vets move to every other day until ovulation is confirmed, and Dr. Fontaine notes it usually takes at least three or four tests to pin it down. If you're fitting progesterone tests for dogs around work or travel, ask your clinic how they handle short-notice appointments before her season arrives.

This is the plan most breeders follow with their vet. Expect your vet to adjust each step for her history, her breed and the semen you're using.

A progesterone test on dogs is an ordinary blood draw, but where the sample goes changes how fast and how precise the answer is. The AKC's chief veterinarian, Dr. Jerry Klein, calls radioimmunoassay the gold standard and notes it is mostly found at veterinary teaching hospitals and large reference labs. Some clinics run chemiluminescence tests that return results in about an hour, and many now have quantitative analyzers that report during the visit.

Progesterone is the same molecule in every mammal, so the progesterone test canine patients get doesn't need a dog-only chemistry. Dr. Fontaine notes that most machines used for dogs were first developed for human medicine. What matters is that the method is quantitative, checked against dog samples, and read by someone who knows that machine's quirks.

Table 4. Comparing progesterone tests for dogs

Not every heat follows the textbook curve. Sometimes progesterone levels for dogs rise toward ovulation and then fall back. Dr. Fontaine calls this an anovulatory cycle: the follicles grow, then shrink without releasing eggs, and she can't get pregnant that heat. He describes one female who reached 4.9 ng/mL before dropping. That's why testing continues until ovulation is confirmed, not just until the LH surge.

A plateau is the other pattern to watch. After ovulation, the level should keep climbing. If it stalls around the same value, he advises close follow-up, and if it stays flat for more than about three days, an ovarian ultrasound to rule out a cyst.

Finally, don't assume her timing repeats. Dr. Fontaine reports that ovulation timing can vary by up to 40 percent between cycles, so a female who ovulated on day 17 last time may not do so again. Test every heat you plan to breed.

Your testing log keeps paying off after the breeding. In a study published in Theriogenology, Kutzler and colleagues counted 65 days from the first preovulatory rise in progesterone, the LH surge reading. The prediction was right within two days for 90 percent of females and within three days for all of them, regardless of body weight or litter size. That's a much tighter estimate than counting from a mating date, since matings can happen days before or after ovulation.

That precision matters most for females who may need a C-section. Dr. Gail McRae of The Ohio State University College of Veterinary Medicine told Purina Pro Club that knowing the LH surge and ovulation gives a three-day window for the due date, which is why she recommends progesterone testing for those females.

During pregnancy, progesterone stays high. The Virginia-Maryland researchers note that a pregnancy is at risk if levels fall below 2 ng/mL, the threshold for maintaining it. Any decision about progesterone support belongs to your vet, so never supplement on your own.

Dr. Fontaine notes that females ovulate at about the same progesterone level whatever their size, from a Chihuahua to a Mastiff. The chart stays the same. What changes is the planning around it.

Yorkshire Terriers and other toy breeds

Small females follow the same curve, so don't expect a lower ovulation number because she weighs a few pounds. If you're comparing Yorkshire Terrier partners in other states, your timing also decides whether shipped chilled semen is realistic, since it has to arrive close to the post-ovulation window.

German Shepherd Dogs and large breeds

Larger breeds tend to have their first heat later, according to AKC veterinary contributors, but once she's cycling the progesterone landmarks don't move. For German Shepherd Dog breedings using frozen semen from a distant stud, the tight frozen timing in Table 3 applies just the same.

French Bulldogs and flat-faced breeds

For breeds where your vet may recommend a planned C-section, like the French Bulldog, progesterone testing earns its keep twice: once for breeding day and again for a due date your vet can schedule around. Talk through delivery plans before she's bred, not after.

A canine progesterone levels chart is most useful when you read it as a story told over several tests: a baseline under 1 ng/mL, a rise through 2 to 3 for the LH surge, roughly 5 to 6 at ovulation, then about two days for her eggs to mature. Build your breeding dates from that ovulation estimate, match them to your semen type, and keep the whole series on one lab.

Call your vet the moment the numbers stop behaving. Every progesterone dog result you log this heat also sets you up for a calmer due date and a better plan next time.