Progesterone Testing & Breeding Window

Overview

Dialing in timing is half the battle in successful Dalmatian breeding. Progesterone testing turns guesswork into a plan-whether you're doing a natural tie down the road or shipping semen across the country. This guide explains how to read numbers, choose a testing cadence, coordinate natural vs. AI breedings, and estimate due dates for whelping or C-section planning. It's written for North American breeders, in plain language, aligned with AKC and theriogenology best practices.

Why it matters: Ovulation is predictable if you track hormones. Puppies (and peace of mind) follow.

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The hormone snapshot: what the numbers mean

Progesterone is low in early heat, rises after the LH surge, and continues upward through ovulation and beyond. You're not breeding to the LH surge; you're breeding to when the eggs mature-about two days after ovulation.

• Typical lab units: ng/mL
• Important anchors (approximate; lab methods vary):
  • <1.0: Early proestrus; not fertile
  • ~2.0: LH surge (Day 0 benchmark)
  • 4-6: Ovulation (often Day 2 after LH)
  • 8-12: Peak fertility window opens (eggs mature ~48 hours post-ovulation)
  • 15-25+: Past ideal for natural/fresh if male fertility or access is limited; still workable for frozen with TCI in many cases

Tip: Stick to one lab or analyzer per cycle. Cross-lab results can differ, and consistency makes interpretation clearer.

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Quick timing guide by semen type

Think “ovulation day” as your pivot. Most bitches ovulate when progesterone lands around 5-6 ng/mL. Eggs need ~48 hours to mature.

• Natural tie or fresh AI
  • Ideal: 2 and 4 days post-ovulation
  • Backup: One breeding ~2-3 days post-ovulation can still hit the window
• Chilled/extended
  • Ideal: 3-4 days post-ovulation (ship to arrive just-in-time)
  • Backup: A single well-timed insemination is often enough with quality semen
• Frozen semen (intrauterine/TCI or surgical)
  • Ideal: 3-5 days post-ovulation (narrow window; precise timing with a repro vet)
  • Consider: One insemination, precisely placed, can outperform two poorly timed ones

Internal link: See whelping prep once you’ve bred: Whelping kit checklist

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Step-by-step: a practical testing plan

Every bitch is different. Build a plan, then adjust to her curve.

1. Start the clock

   • Day 1 of heat = first day of bloody discharge.
   • Record daily behavior, discharge, vulvar changes.

2. Begin testing

   • Common cadence: First progesterone draw around Day 7-9.
   • If <1.5 ng/mL, repeat in 48 hours; if 1.5-3.0 ng/mL, test again in 24-48 hours; if >=3.5 ng/mL, switch to daily testing.

3. Catch the jump

   • The "rise" from ~2 to ~5-6 usually signals ovulation within ~48 hours of the LH surge mark.
   • Log numbers with dates, time collected, and lab used.

4. Plan the breeding(s)

   • Natural/fresh: Book breedings 2 and 4 days after ovulation.
   • Chilled: Coordinate collection/shipping to land 3-4 days after ovulation.
   • Frozen: Schedule TCI with your repro vet for 3-5 days post-ovulation.

5. Confirm the plan fits reality

   • If behavior and discharge don't match the numbers (it happens), trust the numbers-progesterone is more reliable than "standing."

6. Post-breeding

   • Note breeding dates and method; you'll need them for due-date math and veterinary planning.

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Reading results across labs (and avoiding traps)

• Methods differ: RIA, chemiluminescence, in-house analyzers. Absolute values can shift by platform.
• One lab per heat: Consistency trumps theoretical accuracy.
• Timing over thresholds: The pattern and rate-of-rise matter more than a single “magic number.”
• Hemolysis or lipemia can skew results: Ask your vet’s lab about sample quality and handling.

Consider a “home stretch” cadence:

• Early: every 48 hours until >=3 ng/mL
• Approaching ovulation: daily until you confirm the rise past ~5-6 ng/mL
• If shipping chilled/frozen: stay daily until semen is placed

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Pairing progesterone with vaginal cytology (and behavior)

Numbers lead, but cytology and signs add context.

• Proestrus smear: Many RBCs; parabasal/intermediate cells; neutrophils common.
• Estrus smear: Predominantly superficial/anuclear cells; RBCs taper; neutrophils usually absent.
• First day of diestrus: Abrupt shift back to intermediate/parabasal cells-useful for due-date math if you missed ovulation.

Behavior varies. Some Dalmatians “stand” early or late. Some don’t read the textbook at all. That’s okay-follow the hormone curve.

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Due-date math you can trust

Gestation is consistent when you time from hormones, not from breeding date.

• ~65 days from LH surge (Day 0)
• ~63 days from ovulation
• ~57 ± 1 days from first day of diestrus
• 58-72 days from breeding is normal only because breedings happen at variable times

Planning a C-section?

• Best accuracy comes from LH or ovulation timing, plus late-pregnancy fetal monitoring (ultrasound heart rates, GI peristalsis, kidney mineralization) and maternal progesterone drop near term. Coordinate with your repro vet.

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Troubleshooting uncommon curves

• Split heat: Early rise, then a lull. Keep testing; breed only on the true rise to and beyond ~5-6 ng/mL.
• Silent heat: Minimal external signs. Progesterone + cytology can still find ovulation.
• Flat numbers, then a leap: Don’t panic. Ovulation can “arrive” quickly; be ready to pivot.
• High numbers before behavior “looks right”: Trust the lab. Breed on the numbers, especially for shipped or frozen semen.
• Missed the window? If you’re at >=15-20 ng/mL and access is limited, consult your repro vet. Precision TCI with frozen may still salvage timing; otherwise, regroup for next cycle.

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Example timing table (guide, not gospel)

Note: Lab-to-lab differences exist. Your local repro vet’s thresholds take precedence.

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Logistics for shipped semen (chilled and frozen)

• Communication is king: Align stud owner, collecting vet, shipping carrier, and your repro vet before the cycle starts.
• Paperwork ready: Contracts, health testing on file, and clear instructions for extenders and packaging.
• Ship for arrival, not departure: Target arrival 3-4 days post-ovulation for chilled; schedule TCI for frozen 3-5 days post-ovulation.
• Have a Plan B: Weather delays happen. Know your airport cargo hours and the nearest 24/7 ER with repro capability.

Internal link: Pre-breeding health screening matters just as much as timing: Canine Health Testing Guide

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Special notes for Dalmatians

• Athletic bitches can mask external signs; rely on progesterone over behavior.
• Plan urination breaks when traveling to a stud; hydration supports urinary health in a breed with HUU considerations.
• Keep records across cycles. Many Dalmatians are remarkably consistent heat-to-heat; next time gets easier.

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Record-keeping checklist

• Heat day count and daily notes (discharge, swelling, behavior)
• Progesterone date/time, value, and lab method
• Cytology snapshots (mark the day you see diestrus)
• Breeding method, dates, stud details
• Shipment tracking numbers (if used)
• Vet visit notes, ultrasound/X-ray dates
• Targeted due date(s) based on LH/ovulation/diestrus

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FAQs

How often should I test?

Every 48 hours early on, then daily as you approach ovulation (numbers around 3-6 ng/mL). If shipping or using frozen, daily around the rise is worth it.

Can I time with behavior alone?

Sometimes, but you risk missing the true window. Progesterone testing dramatically improves conception rates, litter size, and sanity.

What if my lab’s “ovulation” cutoff is different?

Follow your lab’s validation and your repro vet’s thresholds. The pattern (rising trend) and interval since the rise matter more than any single cross-lab number.

Is one well-timed breeding enough?

Often yes, especially with fresh/chilled of excellent quality or frozen via precise TCI. Two breedings can add insurance for natural/fresh when travel is easy.

How do I predict the due date if I missed ovulation?

Mark the first day of diestrus on cytology and count ~57 days. Use late-pregnancy fetal monitoring to refine C-section timing if needed.

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Work with your repro team

This guide is practical, not a substitute for veterinary care. A theriogenologist or repro-savvy veterinarian can tailor timing to your bitch, your stud, and your method-especially for frozen semen or when prior breedings were missed.

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External resources

• Society for Theriogenology (canine reproduction) - https://therio.org
• AKC Canine Reproduction resources - https://www.akc.org/breeder-programs/
• Veterinary teaching hospitals/board-certified theriogenologists - search “ACT theriogenology directory”

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Related guides on this site

• Dalmatian Breeding Guide - /
• Canine Health Testing Guide - /canine-health-testing
• Whelping Kit Checklist - /whelping-supplies
• Puppy Socialization & Training Plan - /puppy-socialization
• Puppy Purchase Contract & Aftercare - /puppy-contract