Getting Your Dog Pregnant? What Her Progesterone Levels Should Be


Progesterone testing is an important part of managing breeding in female dogs. This article will explain what progesterone is, normal progesterone levels in dogs, optimal levels for breeding, when to start testing, how testing is done, interpreting results, factors affecting progesterone, risks of improper timing, and provide a conclusion summarizing key points.

Knowing when to breed a female dog is critical for increasing likelihood of pregnancy and having a healthy litter. Progesterone testing allows breeders to identify the optimal days for breeding based on hormone levels. This article provides dog owners and breeders an overview of using progesterone testing to maximize chances of breeding success.

What is Progesterone?

Progesterone is a hormone that plays a key role in the canine reproductive cycle. In female dogs, progesterone is produced by the ovaries and helps prepare the body for pregnancy (NewportHarborVets). Specifically, progesterone is responsible for:

diagram showing the role of progesterone in the canine reproductive cycle

  • Preparing the uterine lining for implantation of fertilized eggs
  • Maintaining pregnancy by supporting the uterine lining and preventing contractions
  • Blocking the release of further eggs from the ovaries during pregnancy

Progesterone levels rise after ovulation, whether or not pregnancy occurs. If pregnancy does occur, progesterone levels remain elevated to support the pregnancy. If no pregnancy occurs, progesterone levels will eventually drop, allowing another heat cycle to begin (WACVet).

Monitoring progesterone is important for breeding dogs because it indicates when ovulation occurs and helps determine the optimal days for breeding or artificial insemination.

Normal Progesterone Levels

Progesterone is a hormone that plays an important role in the reproductive cycle of female dogs. Baseline progesterone levels in non-pregnant female dogs are typically less than 1 ng/ml (source). During the reproductive cycle, progesterone levels fluctuate as follows:

  • During proestrus, levels remain low at 0-1 ng/ml.
  • Levels rise during estrus, peaking around 5-10 ng/ml at ovulation.
  • If pregnancy occurs, levels continue rising to 25-30 ng/ml by day 25 and 60-90 ng/ml by day 40.
  • If no pregnancy occurs, progesterone drops back down after estrus.

By tracking progesterone levels during the cycle, the approximate time of ovulation can be determined to optimize breeding.

Optimal Levels for Breeding

The optimal progesterone level for successful breeding in dogs is generally considered to be 5-10 ng/ml. This indicates the dog is in the ovulation phase of her heat cycle, which is the best time for conception.

Progesterone testing should begin as soon as the female shows the first signs of heat, such as swelling of the vulva and spotting of blood. Testing every 2-3 days will allow you to identify when her levels surpass 2-3 ng/ml, indicating ovulation will occur soon. Once levels reach 5 ng/ml, breeding should commence.

Ideally, breeding should take place when progesterone is between 5-10 ng/ml. Levels above 10 ng/ml indicate the optimal breeding window may be closing. Continued testing after initial rise in levels will help pinpoint the ideal days for breeding.

Timely testing and identification of the ovulation phase is key for successful breeding. Watch for the beginning signs of heat and start testing right away. Monitor rising progesterone until ideal breeding levels are reached.

When to Start Testing

The recommended time to start progesterone testing in dogs depends on the length of the heat cycle:

a vet drawing blood from a dog for progesterone testing

  • For dogs with a 10-12 day heat cycle, testing should begin around day 6 of the heat.[1]
  • For a 14-16 day cycle, testing should start around day 8.
  • For dogs with a long 21+ day cycle, testing can begin around day 10.

Testing too early can result in low baseline progesterone levels that don’t provide useful information for timing. Waiting too long risks missing the LH surge and optimal breeding window.

Once started, testing frequency is important. During the critical fertile period, testing every 1-3 days provides sufficient data to accurately detect the LH surge and ovulation. Daily testing is ideal but can be cost prohibitive. At a minimum, every other day testing allows veterinarians to closely track trends in progesterone levels.[2]

How Testing is Done

There are two main methods for testing a dog’s progesterone levels:

Blood Tests

Blood tests at the vet’s office are the most accurate way to measure progesterone. A veterinarian will draw a blood sample from the dog and send it to a lab for analysis. Results are usually available within 24 hours. According to My Budget Vet, blood tests can reliably detect progesterone levels as low as 0.5-1 ng/ml.

At-Home Tests

There are also at-home test kits available to test progesterone levels using vaginal discharge or saliva samples. These tests involve collecting a sample at home and then mailing it to a lab for analysis. At-home testing can be more convenient but may be less precise than blood tests. According to the AKC, at-home tests typically cannot reliably detect levels below 1-2 ng/ml.

Interpreting Results

When interpreting progesterone test results, it’s important to understand what the number values mean. According to the College of Veterinary Medicine at Michigan State University, progesterone levels can be interpreted as follows:

  • 0-2 nmol/L – Anestrus (not cycling or ready to breed)
  • 2-4 nmol/L – Proestrus (going into heat)
  • 4-10 nmol/L – Estrus (in heat, best time to breed)
  • 10-60 nmol/L – Diestrus (out of heat)
  • >60 nmol/L – Pregnancy

Borderline results in the 2-4 nmol/L range can be ambiguous. It’s recommended to retest every 2-3 days in this range to look for increasing levels, which would indicate estrus. Levels can also temporarily dip during estrus, so a single lower value doesn’t necessarily indicate a dog is out of heat.

Results must always be considered in combination with other clinical signs of heat, such as changes in behavior, appearance of vulvar swelling and discharge, and attraction of male dogs. Progesterone testing is a helpful tool, but visual cues also play an important role in identifying the optimal breeding timeframe.

Factors Affecting Progesterone

a chart showing progesterone levels during different stages of a dog's heat cycle

A dog’s age, breed, and reproductive health can all impact progesterone levels and the ability to get pregnant and carry puppies to term.

Age: Older dogs and younger dogs who are just reaching sexual maturity may have lower progesterone levels or more variability in progesterone, which can make successful breeding more difficult. Peak progesterone levels tend to be reached between 2-6 years of age for most dogs [1].

Breed: Some breeds like German Shepherds and Labradors tend to have higher baseline progesterone levels compared to other breeds like Beagles or Poodles. Breed size and genetic factors play a role [1].

Reproductive Health: Dogs with conditions like cystic ovaries or uterine infections may not produce adequate progesterone. Good overall health leads to better reproductive hormone function [1].

Risks of Improper Timing

Breeding a dog too early or too late can lead to serious issues with fertility and pregnancy.

If a dog is bred too early, before ovulation and peak progesterone levels, the eggs may not be mature enough for successful fertilization. This can result in no pregnancy occurring or early embryonic death. According to research, optimal timing for breeding is 2-3 days after the progesterone peak when eggs are mature [1].

Breeding too late, after ovulation, can also cause problems. As progesterone levels drop following ovulation, egg quality and uterine receptivity decline. This decreases chances of fertilization and proper implantation in the uterus. One study found pregnancy rates dropped from 84% to 33% when breeding occurred 5 days after ovulation [2].

Getting the timing right within that fertile window around ovulation and peak progesterone is key for breeders seeking successful pregnancies and healthy litters.


When trying to breed dogs, monitoring progesterone levels is important for determining the optimal timing. The ideal progesterone range for breeding a dog is generally 2-10 ng/ml. Levels below 2 ng/ml indicate the female is not ready, while levels above 10 ng/ml suggest ovulation is imminent. Starting testing around the estimated time of heat and continue every 2-3 days until ovulation is confirmed.

Work closely with your veterinarian, as they can help interpret results and account for individual factors. Be patient through the process. While tempting, avoid breeding too early or late based on progesterone alone. With the right testing and timing, you can hopefully achieve success!

a happy breeder with a pregnant dog after successful progesterone-guided breeding

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