# Progesterone Testing in Canine Breeding Management


## Key Takeaways

- Serial progesterone measurement is the gold standard for timing ovulation in bitches, as spontaneous ovulation lacks reliable external signs; progesterone rises predictably relative to the LH surge and ovulation, typically reaching 2-5 ng/mL at ovulation.
- The optimal breeding window is generally 2-4 days post-ovulation, necessitating frequent sampling (daily once concentrations rise) to accurately pinpoint this period, especially crucial for chilled or frozen semen.
- Assay platforms vary in performance; while RIA is a reference method, ELISA and CLIA offer in-house or faster turnaround times, but clinicians must be aware of platform-specific thresholds and potential inaccuracies with whole blood samples in some ELISA systems.
- Interpretation relies on the rate of progesterone increase, not a single value; a rise from <1 ng/mL to >2 ng/mL over 48 hours indicates preovulatory luteinization, while a rise to >5 ng/mL signals imminent or recent ovulation.
- Common errors include starting testing too late, infrequent sampling, switching assay platforms mid-cycle, and neglecting clinical signs like vaginal cytology; consistent documentation of assay type, sample matrix, and clinical findings is critical for accurate interpretation and future cycle management.

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Serial progesterone measurement is the standard method for timing ovulation and scheduling breeding in the bitch. This article provides the practicing veterinarian with a clinical framework for interpreting progesterone concentrations across the periestrous period, selecting among available assay platforms, and translating results into breeding recommendations. The content assumes familiarity with canine reproductive physiology and focuses on the procedural decisions that determine success in clinical breeding management.

The bitch is unique among domestic species in that ovulation occurs spontaneously but the preovulatory luteinizing hormone (LH) surge and subsequent ovulation are not accompanied by reliable external signs in all individuals. Vaginal cytology and vulvar examination provide supportive information, but neither predicts ovulation with the temporal precision required for optimal conception rates, particularly when chilled or frozen semen is used. Progesterone measurement addresses this limitation directly because the hormone rises in a predictable sequence relative to the LH surge and ovulation.

This article covers the endocrine basis for progesterone testing, the performance characteriztics of available assay types, recommended sampling protocols, and interpretation of results across the breeding window. It also addresses common sources of error and clinical scenarios where progesterone data must be weighed against other findings.

## At a Glance

| Parameter | Clinical Relevance |
|---|---|
| Progesterone at ovulation | Typically 2 to 5 ng/mL at the time of ovulation in most assay systems |
| Optimal breeding window | Days 2 to 4 after the first rise above baseline, corresponding to the postovulatory period |
| Sampling frequency | Every 2 to 3 days in early proestrus, daily once concentrations begin to rise |
| Assay types | Radioimmunoassay, enzyme-linked immunosorbent assay, chemiluminescent immunoassay, and point-of-care devices |
| Whole blood | Unreliable for some ELISA platforms, plasma or serum preferred |
| Confounding factors | Luteal cysts, exogenous progestins, assay drift, and interlaboratory variation |
| Clinical integration | Combine with vaginal cytology, vaginoscopy, and semen evaluation for breeding decisions |

## Endocrine Basis of Progesterone Measurement

The reproductive cycle of the bitch begins with proestrus, during which follicular development proceeds under rising estrogen concentrations. The preovulatory LH surge occurs approximately 24 to 48 hours before ovulation, and the first significant rise in progesterone above baseline is detected at or shortly after this surge. Progesterone concentrations then increase steadily as luteinization of the ovulating follicles progresses.

The temporal relationship between progesterone and ovulation is the foundation of clinical testing. In most assay systems, ovulation occurs when progesterone reaches approximately 2 to 5 ng/mL, and the oocytes remain fertilizable for 48 to 72 hours after ovulation. This window is the target for breeding, and the goal of serial testing is to identify the day of ovulation with sufficient precision to schedule matings or inseminations.

The Society for Theriogenology provides professional resources on reproductive management, including guidance on the interpretation of endocrine data in breeding soundness evaluation and ovulation timing [Society for Theriogenology resources](https://www.therio.org/). The MSD Veterinary Manual similarly addresses the clinical application of progesterone testing in canine breeding management as part of its species-specific reproductive medicine content [MSD Veterinary Manual](https://www.msdvetmanual.com/).

## Assay Platforms and Their Performance

### Radioimmunoassay

Radioimmunoassay (RIA) has historically been the reference method for canine progesterone measurement. It offers high sensitivity and specificity, and results are reported in ng/mL with well-established reference ranges. The principal limitations are the requirement for specialized laboratory facilities, the handling of radioactive materials, and the delay between sample collection and result availability. For practices that send samples to external laboratories, the turnaround time may be 24 to 72 hours, which is acceptable for early monitoring but problematic when daily sampling is needed near ovulation.

### Enzyme-Linked Immunosorbent Assay

Enzyme-linked immunosorbent assay (ELISA) platforms were developed to provide in-house testing with results available within 30 to 60 minutes. A comparative evaluation of the ICAGEN-Target canine ovulation timing ELISA against RIA in 166 canine plasma samples found overall agreement of 85%, with agreement of 96% at high concentrations (5 ng/mL or greater), 73% at medium concentrations (greater than 1 ng/mL and less than 5 ng/mL), and 77% at low concentrations (0 to 1 ng/mL) [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/). The same study reported that whole blood produced unreliable results compared with plasma, emphasizing the need for careful sample handling when using ELISA platforms.

The medium concentration range is precisely the interval during which ovulation occurs, so the reduced agreement in this range has direct clinical consequences. The authors of that evaluation recommended beginning testing within three to four days after onset of proestrus and continuing every other day until medium concentrations are first detected, then switching to daily testing through the transition to high concentrations. They further recommended breeding on the second or third day after the first appearance of high concentrations.

### Chemiluminescent Immunoassay and Point-of-Care Devices

Chemiluminescent immunoassay (CLIA) platforms are available through reference laboratories and some in-house analyzers. These systems offer quantitative results with performance characteriztics comparable to RIA in most published evaluations. Point-of-care devices vary widely in their analytical performance, and the clinician should establish the reference ranges and interpretive criteria specific to the device in use before relying on absolute values for breeding decisions.

## Sampling Protocol

The sampling schedule determines the clinical utility of progesterone data. Testing too early or too infrequently can miss the critical transition from baseline to ovulatory concentrations. The protocol recommended in the ICAGEN-Target evaluation provides a reasonable template: begin sampling within three to four days after the onset of proestrus, continue every other day until medium concentrations are detected, then sample daily until high concentrations are confirmed [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/).

This schedule balances the need for temporal resolution against the practical constraints of client compliance and cost. Bitches with a history of prolonged proestrus may require earlier initiation of testing, while those with short proestrus may transition through the critical range rapidly. The clinician should adjust the protocol based on the individual patient and the breeding plan.

## Interpretation of Progesterone Concentrations

Serial progesterone measurement is interpreted against a well-established endocrine framework. The transition from basal concentrations to a sustained rise marks the preovulatory luteinization of follicular cells, which precedes ovulation by approximately 24 to 48 hours in the bitch. Ovulation itself occurs at or shortly after the progesterone concentration first exceeds 5 ng/mL in most assay systems, although the precise threshold varies with the platform used.

The clinical goal is not to identify a single absolute value but to detect the rate of change across serial samples. A rise from less than 1 ng/mL to greater than 2 ng/mL over 48 hours indicates that the preovulatory surge has begun. A further rise to 5 ng/mL or greater signals that ovulation is imminent or has just occurred. The optimal breeding window typically spans from 2 to 4 days after the first detection of elevated progesterone, depending on the semen type and breeding method.

### Assay-Specific Thresholds

Different assay platforms yield different absolute values for the same physiologic state. A chemiluminescent immunoassay may report a progesterone concentration of 4 ng/mL at a time when a radioimmunoassay on the same sample reports 6 ng/mL. The clinician must therefore interpret results in the context of the specific laboratory or point-of-care device used, not against a universal scale.

For enzyme-linked immunosorbent assay systems, the agreement with radioimmunoassay is strongest at high concentrations. In an evaluation of the ICAGEN-Target ELISA kit against radioimmunoassay across 166 canine samples, overall agreement was 85%, with agreement of 96% at concentrations of 5 ng/mL or greater, 73% at concentrations between 1 and 5 ng/mL, and 77% at concentrations of 1 ng/mL or less. The same study reported that whole blood produced unreliable results compared with plasma, so sample type must be standardized across the monitoring series. When using that ELISA platform, the authors recommended starting testing within three to four days after onset of proestrus, testing every other day until medium concentrations are detected, then testing daily through the transition to high concentrations. The recommended breeding day was the second or third day after the first appearance of high concentrations.

### Monitoring Parameter Table

| Progesterone concentration (plasma, RIA-equivalent) | Reproductive stage | Clinical action |
|---|---|---|
| Less than 1 ng/mL | Anestrus, early proestrus, or nonpregnant luteal phase | Begin serial testing if proestrus signs are present, repeat in 2 to 3 days |
| 1 to 2 ng/mL | Late proestrus, preovulatory luteinization begins | Repeat testing every 48 hours |
| 2 to 5 ng/mL | Preovulatory LH surge underway or completed | Repeat testing every 24 hours, consider breeding with chilled or frozen semen |
| 5 to 10 ng/mL | Ovulation occurring or recently completed | Optimal window for natural mating or fresh AI, continue daily testing |
| 10 to 20 ng/mL | Postovulation, early luteal phase | Breeding still possible but less optimal, confirm with vaginal cytology or ultrasound |
| Greater than 20 ng/mL | Mid-luteal phase | Breeding window closed, assess for pregnancy after day 25 to 30 |

The thresholds in this table assume a radioimmunoassay or chemiluminescent platform calibrated to similar standards. For point-of-care ELISA devices, the clinician should adjust thresholds according to the manufacturer's validated ranges and the published performance data for that specific kit.

## Decision Points in Breeding Timing

The first decision point occurs when the progesterone concentration rises above 2 ng/mL. At this stage, the clinician must determine whether to continue daily monitoring or proceed with breeding. For bitches with a known history of ovulation timing, the pattern from previous cycles can guide this decision. For maiden bitches or those with irregular cycles, daily monitoring is safer.

The second decision point occurs when the concentration reaches 5 ng/mL. Ovulation typically follows within 24 to 48 hours. The oocyte then requires an additional 48 to 72 hours of maturation in the oviduct before fertilization is possible. This means the optimal insemination window extends from approximately 2 to 5 days after the progesterone first exceeds 5 ng/mL.

Semen type changes the timing. Fresh semen has a longer viable lifespan in the reproductive tract and can be inseminated earlier in the window. Chilled semen should be inseminated closer to the middle of the window. Frozen semen, with the shortest viability, should be inseminated at the end of the window, often 3 to 4 days after ovulation, to ensure that capacitated spermatozoa meet mature oocytes.

### When the Pattern Is Atypical

A progesterone concentration that rises and then plateaus without reaching the expected peak may indicate luteal insufficiency or a nonovulatory follicle. A concentration that rises rapidly over 24 hours suggests that the clinician may have missed the early rise and should breed sooner than the standard protocol would indicate. A concentration that remains below 2 ng/mL despite 10 days of proestrus signs warrants investigation for ovarian cyst, silent heat, or assay error.

## Troubleshooting Ambiguous Results

| Problem | Possible cause | Action |
|---|---|---|
| Progesterone lower than expected for clinical signs | Assay error, sample handling delay, hemolysis, or use of whole blood with an ELISA validated for plasma | Repeat the test on a fresh plasma sample, confirm the assay platform and sample type match the validation protocol |
| Progesterone higher than expected for clinical signs | Prior luteal phase, pregnancy, or assay cross-reactivity | Correlate with vaginal cytology and physical examination findings, repeat in 24 hours |
| Two consecutive samples show no change | Sampling interval too long, assay insensitivity at low concentrations, or laboratory error | Shorten the sampling interval to 24 hours, consider a different assay platform |
| Progesterone rises then falls before breeding | Luteal insufficiency, follicular atresia, or assay variability | Repeat testing immediately, if confirmed, evaluate ovarian ultrasound and consider hormonal support |
| Point-of-care device and reference laboratory disagree | Calibration differences between platforms | Use one platform consistently throughout the monitoring series, if switching, run parallel samples to establish a conversion factor |

Sample handling errors are a common source of ambiguous results. Plasma should be separated from cells within 30 minutes of collection and refrigerated if testing is delayed beyond a few hours. Hemolyzed samples can produce falsely low readings on some immunoassay platforms. The clinician should document the sample type, collection time, and assay platform for every sample in the series.

## Documentation and Record Keeping

Each progesterone value should be recorded with the date, time, assay platform, sample type, and the corresponding physical findings. Vaginal cytology findings, vulvar swelling, and behavioral estrus signs should be logged alongside the hormone values. This record serves two purposes. It allows the clinician to identify the rate of rise across the current cycle, and it builds a cycle history for the individual bitch that informs future breeding management.

A standardized form or spreadsheet with columns for date, cycle day, progesterone value, assay platform, vaginal cytology stage, and breeding action taken is practical. The record should also note the semen source and insemination method for each breeding, as this information is needed to evaluate conception success and to adjust timing in subsequent cycles.

For bitches bred repeatedly over several seasons, the historical pattern of progesterone rise is often remarkably consistent. A bitch that ovulated on day 3 after reaching 2 ng/mL in one cycle is likely to follow a similar pattern in subsequent cycles. This predictability allows the clinician to reduce the number of samples needed in later cycles, though confirmation of the pattern in at least two cycles is advisable before relying on it.

## Equipment and Consumable Choices

The choice of assay platform depends on the practice setting, caseload, and laboratory access. Practices with a high volume of breeding management may invest in an in-house chemiluminescent immunoassay analyzer. Practices with lower caseloads may prefer to send samples to a reference laboratory, accepting a 24-hour turnaround in exchange for lower equipment costs.

Point-of-care ELISA devices offer rapid results but require careful attention to validation. The ICAGEN-Target evaluation demonstrated that whole blood produced unreliable results compared with plasma, so the clinician must verify that the sample type used in practice matches the sample type used in the kit's validation studies. The same principle applies to any point-of-care device: the clinician should review the published performance data for that specific kit and adjust interpretive thresholds accordingly.

The sampling interval should be tailored to the assay platform. For ELISA systems with lower sensitivity in the medium range, more frequent sampling is needed during the transition from medium to high concentrations. For high-sensitivity chemiluminescent platforms, sampling every 48 hours until the rise begins, then daily thereafter, is usually sufficient.

Patient status changes the protocol. A bitch with a history of prolonged proestrus or irregular cycles may require more frequent sampling. A bitch with a known ovulation pattern from previous cycles can be sampled less frequently. The clinician should also consider the owner's schedule and the availability of the stud dog or semen, as these practical constraints may shift the breeding window even when the endocrine data are unambiguous.

## Recognized Complications and Failure Modes

Serial progesterone monitoring fails most often through timing errors instead of assay malfunction. The most common failure is starting testing too late. A bitch that presents in late proestrus or early estrus may already have a progesterone concentration above the optimal breeding threshold, and the clinician cannot determine whether the rise occurred one day or three days earlier. This loss of temporal resolution prevents accurate prediction of the luteinizing hormone (LH) surge and forces reliance on secondary signs. Early detection of this problem requires asking the owner for the first day of vulvar swelling or sanguinous discharge and comparing that date against the measured progesterone. If the concentration is already above 5 ng/mL on the first sample and the bitch has been in proestrus for more than seven days, the optimal breeding window may already be closing.

A second failure mode is sampling at intervals too long to capture the transition from baseline to elevated progesterone. The rise from less than 1 ng/mL to greater than 5 ng/mL can occur within 48 hours in some bitches. Testing every third or fourth day can miss the intermediate range entirely, leaving the clinician with a low value on one day and a high value on the next. The discriminating check is to compare the interval between samples against the observed rate of rise. When the interval exceeds two days during the expected transition, the result cannot localize ovulation to a specific day.

Whole blood as a sample matrix produces unreliable results with some enzyme-linked immunosorbent assay (ELISA) platforms. In an evaluation of the ICAGEN-Target ELISA, whole blood yielded progesterone concentrations that did not agree with plasma values measured by radioimmunoassay, while plasma samples showed 85% overall agreement across 166 samples [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/). Clinicians who use point-of-care devices must confirm whether the manufacturer validated the device for serum, plasma, or whole blood. If the package insert specifies plasma or serum, whole blood should not be substituted.

## Common Errors and Corrective Actions

Less experienced clinicians frequently misinterpret a single progesterone value as diagnostic. A concentration of 4 ng/mL means different things depending on whether the previous sample was 0.5 ng/mL or 3.5 ng/mL. The corrective action is to plot serial values on a timeline and interpret the slope, not the absolute number. A rise of 1 ng/mL per day suggests a different ovulation timeline than a rise of 3 ng/mL per day.

Another recurring error is switching assay platforms mid-cycle. A chemiluminescent immunoassay and a point-of-care ELISA may report different absolute values for the same sample, and thresholds validated for one platform do not transfer to another. The corrective action is to use a single assay type throughout a given cycle and to record the platform name in the patient record. When a platform change is unavoidable, the clinician should collect a paired sample and run both assays on the same day to establish a conversion relationship.

A third error is ignoring the clinical examination. Progesterone values guide timing, but vaginal cytology, vulvar swelling, and male interest provide corroborating information. A progesterone value suggesting ovulation in a bitch with no cytologic cornification should prompt a repeat sample and a recheck examination instead of immediate breeding.

## Limitations of Current Evidence

The published evidence base for canine progesterone thresholds is thinner than clinical practice suggests. The widely used threshold of 5 ng/mL for identifying the periovulatory period derives largely from a single evaluation of one ELISA kit, which reported 96% agreement with radioimmunoassay at concentrations of 5 ng/mL or greater but only 73% agreement in the medium range of 1 to 5 ng/mL [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/). That study also recommended breeding on the second or third day after the first high reading, a recommendation that may not transfer to other platforms with different calibration curves.

Expert opinion still differs on whether ovulation occurs at 5 ng/mL, 8 ng/mL, or some other value across assay types. Some specialists advocate using the LH surge as the primary reference point and progesterone as a surrogate, while others treat progesterone thresholds as sufficient on their own. The Society for Theriogenology maintains resources on reproductive management that summarize current recommendations, but these resources do not resolve the underlying calibration differences between assays [Society for Theriogenology resources](https://www.therio.org/). Clinicians should know which assay their laboratory uses and should request the laboratory's own threshold recommendations instead of applying generic values.

## Referral and Escalation Criteria

Referral to a theriogenologist is warranted when serial progesterone values are consistently low despite clear behavioral estrus, when values fluctuate without a sustained rise, or when the bitch fails to conceive after two cycles with apparently correct timing. These patterns suggest anovulation, luteal insufficiency, or a laboratory problem that exceeds the scope of routine practice.

Laboratory involvement is appropriate when point-of-care results conflict with clinical findings or when a single sample must be rechecked on a different platform. A reference laboratory can run radioimmunoassay or chemiluminescent immunoassay on stored serum and provide a definitive value. The clinician should request the laboratory's reference intervals for the specific assay and should ask whether the laboratory validates canine samples specifically.

Regulatory reporting is rarely relevant to routine progesterone testing. It becomes relevant only when samples are collected for forensic purposes, such as disputed parentage or suspected breeding mismanagement, or when the testing is part of a larger investigation. In those cases, chain-of-custody documentation and laboratory accreditation matter more than clinical interpretation. The World Organization for Animal Health publishes standards for diagnostic testing that apply when results cross international borders [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/).

## Troubleshooting Table

| Observation | Likely Cause | Discriminating Check |
|---|---|---|
| First sample already above 5 ng/mL | Testing started too late | Compare against onset of proestrus, check for cytologic cornification |
| Low value followed by high value with no intermediate | Sampling interval too long | Reduce interval to 24 hours during transition |
| Whole blood result does not match plasma result | Matrix incompatibility | Confirm manufacturer validation, switch to plasma or serum |
| Values plateau below 5 ng/mL | Anovulation or luteal insufficiency | Repeat assay on another platform, consider ultrasound |
| Different platforms give different values | Calibration differences | Use one platform per cycle, run paired samples if switching |
| Progesterone high but no behavioral estrus | Silent estrus or timing error | Recheck examination, verify sample identity and timing |

## Frequently Asked Questions

### How Should I Manage Progesterone Testing When a Point-of-Care Analyzer Is Unavailable?

When in-clinic equipment is unavailable, submit serum samples to a commercial laboratory using chemiluminescent immunoassay or radioimmunoassay. Collect samples into plain serum tubes, centrifuge within 30 minutes, and refrigerate if shipping within 24 hours. Frozen serum is acceptable for longer delays. The practical limitation is turnaround time, which typically ranges from 24 to 72 hours. Schedule sampling so results arrive before the expected preovulatory luteinizing hormone surge. For bitches with unpredictable cycles, begin sampling earlier and accept that some samples may be wasted. A handheld ELISA kit validated against radioimmunoassay can serve as a low-cost alternative, but whole blood produces unreliable results, so plasma separation is mandatory [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/).

### What Is the Minimum Sampling Frequency That Still Yields Clinically Useful Results?

Every-other-day sampling from three to four days after proestrus onset is sufficient to detect the transition from basal to medium progesterone concentrations. Once medium concentrations appear, daily sampling becomes necessary because the rise to high concentrations can occur rapidly. The original validation work for the ICAGEN-Target ELISA demonstrated that daily plasma testing during the medium-to-high transition was essential for accurate ovulation timing [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test](https://pubmed.ncbi.nlm.nih.gov/7820766/). For clients with financial constraints, a reduced protocol of every-other-day sampling throughout the entire cycle will still identify the breeding window, but the precision of ovulation day estimation decreases. This compromise is acceptable for natural mating but less ideal for chilled or frozen semen where timing accuracy directly affects conception rates.

### How Do I Explain Serial Progesterone Testing to a Client Who Expects a Single Blood Test?

Clients often assume one measurement provides a definitive answer. Explain that progesterone rises gradually over several days and the clinically relevant information is the rate of change, not a single value. Use a simple analogy: one photograph cannot show how fast a car is moving, but two photographs taken an hour apart can. The first sample establishes the baseline, and subsequent samples reveal whether the bitch is approaching ovulation, has ovulated, or is entering the luteal phase. Emphasize that the cost of additional samples is small relative to the cost of a missed breeding cycle or a failed artificial insemination with shipped semen. Provide the client with a written schedule of planned sampling dates at the initial visit so expectations are set before testing begins.

### When Should I Recommend Referral to a Theriogenologist?

Refer when serial progesterone patterns remain ambiguous despite correct sampling technique and assay calibration. Specific indications include suspected luteal phase defects, bitches with prolonged proestrus exceeding 21 days, cycles where progesterone never exceeds 5 ng/mL, and cases requiring surgical insemination where timing precision is critical. The Society for Theriogenology maintains a directory of board-certified specialists and provides clinical resources for complex reproductive cases [Society for Theriogenology resources](https://www.therio.org/). Referral is also appropriate when the practice lacks the equipment or expertise to perform intrauterine insemination and the case involves valuable genetics or a history of infertility. Early referral is preferable to repeated failed cycles, as each oestrous cycle lost represents a significant delay in the breeding program.

### How Does Progesterone Testing Differ in Other Domestic Species?

Progesterone measurement serves different purposes across species. In cattle, milk progesterone testing is used primarily for pregnancy diagnosis and fertility monitoring instead of ovulation timing, and sampling frequency can be as low as monthly when used for genetic selection purposes [Genetic analysis of postpartum measures of luteal activity in dairy cows](https://pubmed.ncbi.nlm.nih.gov/17183111/). In sows, a single progesterone-based ELISA on day 17 post-breeding identifies non-pregnant animals with acceptable accuracy for commercial herd management [Field experiences with early pregnancy diagnosis by progesterone-based ELISA in sows](https://pubmed.ncbi.nlm.nih.gov/18575064/). In mares, progesterone confirms luteal activity but ovulation timing relies more heavily on follicular ultrasonography. The canine pattern of a rapid preovulatory rise followed by a plateau is relatively unique, so thresholds and sampling intervals developed for dogs do not transfer directly to other species.

### What Records Should I Maintain for Each Progesterone Monitoring Cycle?

Record the assay platform, lot number, and calibration status for every sample. Document the time of day for each collection, as diurnal variation, though minimal, can confound interpretation when comparing serial results. Maintain a graphical plot of progesterone against cycle day for each bitch, which allows rapid visual identification of atypical patterns. Note the clinical signs observed at each sampling visit, including vulvar swelling, discharge character, and male interest. Record the breeding method used, semen quality parameters, and the interval from the detected progesterone rise to each breeding. This documentation supports retrospective analysis when conception fails and provides a baseline for future cycles. The MSD Veterinary Manual recommends maintaining complete reproductive records as part of standard practice management [MSD Veterinary Manual professional resources](https://www.msdvetmanual.com/).

## Related Clinical & Scientific Guides

* [Diagnostic Approach to Canine Infertility in the Bitch](/knowledge/veterinary-medicine/theriogenology/diagnostic-approach-to-canine-infertility-in-the-bitch)
* [Canine Neonatal Resuscitation: Protocol and Monitoring](/knowledge/veterinary-medicine/theriogenology/canine-neonatal-resuscitation-protocol-monitoring)
* [Equine Breeding Soundness Examination of the Stallion](/knowledge/veterinary-medicine/theriogenology/equine-breeding-soundness-examination-of-the-stallion)


## References and Further Reading

- [Evaluation of the ICAGEN-Target canine ovulation timing diagnostic test in detecting canine plasma progesterone concentrations.](https://pubmed.ncbi.nlm.nih.gov/7820766/). 1995.
- [Genetic analysis of postpartum measures of luteal activity in dairy cows.](https://pubmed.ncbi.nlm.nih.gov/17183111/). 2007.
- [Observations on the use of GonaCon in captive female elk (Cervus elaphus).](https://pubmed.ncbi.nlm.nih.gov/19204347/). 2009.
- [Serum anti-Müllerian hormone dynamics in mares following immunocontraception with anti-zona pellucida or -GnRH vaccines.](https://pubmed.ncbi.nlm.nih.gov/29096268/). 2018.
- [Population-based anti-Müllerian hormone reference intervals help define gonadal status in the bitch.](https://pubmed.ncbi.nlm.nih.gov/39260407/). 2025.
- [Field experiences with early pregnancy diagnosis by progesterone-based ELISA in sows.](https://pubmed.ncbi.nlm.nih.gov/18575064/). 2008.
- [Society for Theriogenology Resources](https://www.therio.org/). Society for Theriogenology.
- [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual.
- [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association.

## Related Articles

- [Breeding Soundness Examination of the Canine Male](/knowledge/veterinary-medicine/theriogenology/breeding-soundness-examination-of-the-canine-male)
- [Feline Breeding Management: Estrus Detection and Mating](/knowledge/veterinary-medicine/theriogenology/feline-breeding-management-estrus-detection-and-mating)
- [Canine Progesterone Monitoring: Timing and Interpretation](/knowledge/veterinary-medicine/theriogenology/canine-progesterone-monitoring-timing-and-interpretation)
- [Caprine Reproductive Management: Estrus Detection and Breeding](/knowledge/veterinary-medicine/theriogenology/caprine-reproductive-management-estrus-detection-breeding)
- [Dystocia Management in the Bitch: Decision-Making and Intervention](/knowledge/veterinary-medicine/theriogenology/dystocia-management-in-the-bitch-decision-making-and-intervention)

> This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.