Reproduction Testing: Timing, Confirming, and the Order That Matters
Quick Answer — Breeding management uses two hormones for two different questions, and the most common failure is using them in the wrong order. Progesterone times ovulation and therefore insemination; relaxin confirms placental tissue later. A clinic that reverses the sequence will conclude one of the products is unreliable when the sequence, not the assay, was wrong.
Quick Answer
Progesterone for the window. Relaxin for the answer. Ultrasound for the details.
The two questions
| Question | Test | Timing | What it cannot do |
|---|---|---|---|
| When should she be bred? | Progesterone series | Periovulatory, every 48 h | Confirm pregnancy |
| Is she pregnant? | Relaxin | After the validated detection day | Time breeding |
| How many, and viable? | Ultrasound | Later in gestation | Predict ovulation timing |
The progesterone series, done properly
- Start at first detection of oestrus, not on a calendar day.
- Sample at a fixed interval, commonly 48 hours.
- Continue until the threshold is bracketed — one value below, one above, same platform.
- Time insemination from the bracket, not from a single reading.
- Stop once well past ovulation — the luteal plateau carries no timing information.
Data pending. This section reports measured values from internal validation studies. They are published once the supporting study is complete; the current report is available from technical support on request.
Why pseudopregnancy matters
An elevated progesterone confirms a luteal phase, which occurs whether or not the bitch conceived. Relaxin is the test that distinguishes the two, and it is the reason a negative relaxin at the correct interval is genuinely informative: it changes the conversation from “wait and see” to “this is hormonal”.
The repeat breeder
Before investigating infertility, establish whether the cycle was actually managed:
| Question | If the answer is unclear |
|---|---|
| Was ovulation confirmed by a series? | The record, not the bitch, is the first problem |
| Was insemination timed to the bracket? | Timing error is a common cause of “infertility” |
| Was the same platform used throughout? | A platform change can mimic a stall or a rise |
| Was relaxin run at the validated interval? | An early negative is uninterpretable |
Data pending. This section reports measured values from internal validation studies. They are published once the supporting study is complete; the current report is available from technical support on request.
Monitoring an established pregnancy
Progesterone is not a pregnancy-monitoring test in routine use, and serial progesterone in a confirmed pregnancy should follow a specific clinical indication rather than habit. Where supplementary progesterone is being considered, the decision belongs to the clinician and the reproductive guidance in use, not to a threshold table.
Six traps
- Timing breeding with relaxin. Wrong hormone, wrong question.
- A single progesterone value. The curve carries the information.
- Irregular sampling intervals. Slope interpretation collapses.
- Changing platform mid-cycle. Bias shift mimics biological change.
- Interpreting an early negative relaxin as “not pregnant”. Retest at the validated interval.
- Working up infertility without cycle records. The commonest missed cause is timing.
The Author’s Take
Position. Reproduction is the segment where a vendor’s best product is a protocol, and the clinics that adopt one become the most loyal customers in the menu.
Reasoning. Progesterone and relaxin are both commodities; several suppliers have them. What a breeder or a reproduction clinic cannot buy easily is consistency — the same schedule, the same interpretation rule, the same record format across staff and seasons. Supplying that turns two assays into a managed programme, reduces the support burden dramatically (most “test failure” calls in this segment are timing calls), and generates predictable repeat testing. It is also the rare case where a vendor can improve outcomes without needing better data: the data is already good enough; the workflow is what fails.
Disclosure. Written from published canine reproductive endocrinology; no new experimental data. Values marked are placeholders for Migibio’s platform data and the guidance adopted by medical affairs.
Related pages
Sources
- Reference to be added.
- Reference to be added.
- Reference to be added.
Frequently asked questions
- In what order should progesterone and relaxin be used?
- Progesterone first, to time ovulation and insemination. Relaxin later, after implantation, to confirm pregnancy. Reversing the order is a category error: by the time relaxin is detectable, the fertile window has closed.
- What does a high progesterone mean if the bitch is not pregnant?
- That ovulation occurred and the luteal phase is present. Progesterone rises after ovulation and stays elevated whether or not conception happens, so it confirms ovulation, not pregnancy. A pseudopregnancy produces the same luteal pattern.
- How should a repeat breeder be worked up?
- Start with cycle documentation: was ovulation actually confirmed, and was insemination timed to it. Many repeat breeders have a timing problem rather than an infertility problem. Where timing is documented and correct, move to uterine and hormonal assessment.