Progesterone testing in dogs: when to breed
How progesterone testing times a dog breeding: when to start, what the first rise means, which days to breed, and when LH testing is worth it, following the Merck Veterinary Manual.
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Short answer
Your veterinarian starts progesterone tests once vaginal cytology shows the heat is well under way, usually every other day. The day progesterone first rises above about 1.5 to 2.5 ng/mL is day zero; the Merck Veterinary Manual advises breeding between days 3 and 6 and a new test two to three days later to confirm ovulation (above 5 ng/mL). Frozen or chilled semen calls for tighter timing with LH testing.
Choose this if
A calendar note works for a single breeding with fresh semen and a vet who keeps the results.
Choose the other option if
Littero helps when you track several females, keep every progesterone result on a chart and plan the whelping window from the right date.
At a glance
| Feature | Paper notes | Littero |
|---|---|---|
| Records each progesterone result | Yesby hand | Yeson a chart |
| Heat cycle calendar per female | Partly | Yes |
| Whelping window from the mating dates | No | Yesa range, never a single date |
| Reminders for tests and vet visits | No | Yes |
| Several females and litters | Partly | Yes |
Why time a breeding at all
The breeding date is a poor predictor: fresh canine semen can live in the tract for nine days or more, so a mating days before the fertile window can still produce a litter. Ovulation is what counts, and the fertile window around it lasts about four days.
Timing matters most when semen is chilled, shipped or frozen, when the stud dog is subfertile, when the stud allows only a couple of breedings, or when you want a precise due date, for example to plan a cesarean.
When to start testing
Tell your veterinarian when you first see the signs of heat: discharge, a swollen vulva and interest from males. Even an attentive owner can miss the first few days.
Merck describes checking vaginal cytology during proestrus and starting hormone tests once more than 70% of the cells are superficial cells. From then on, progesterone is usually tested every other day.
Reading the results
- Day zero: the day progesterone first rises above about 1.5 to 2.5 ng/mL.
- Breeding: advised between days 3 and 6 after day zero for routine breedings.
- Confirmation: a test two to three days later should show more than 5 ng/mL, confirming that ovulation happened.
- Frozen or chilled semen, infertility and subfertile studs: add LH testing, drawing blood daily and testing the stored sample from the day progesterone first rose.
From ovulation to whelping
Once ovulation is known, the due date narrows to a few days: pregnancy lasts about 62 to 64 days from ovulation, against 58 to 72 days counted from a breeding date. Our free dog due date calculator turns either date into the whelping window and the checkup dates.
Laboratories use different methods, so compare results from the same lab and let your veterinarian interpret them.
Frequently asked questions
When should I start progesterone testing my dog?
When your veterinarian sees, on vaginal cytology, that the heat is well under way (more than 70% superficial cells). Tests usually follow every other day.
What progesterone level means ovulation in dogs?
The first rise above about 1.5 to 2.5 ng/mL marks day zero; a level above 5 ng/mL two to three days later confirms ovulation, according to the Merck Veterinary Manual.
When is the best time to breed a dog after the progesterone rise?
Merck advises breeding between days 3 and 6 after the initial rise for routine breedings.
Do I need LH testing too?
For frozen or chilled semen, infertility cases and subfertile studs, LH testing gives more precise timing. For routine fresh breedings, progesterone is usually enough.
Is Littero available?
See the official app page for current availability and pricing.
Our pick
Littero, the kennel book for dog breeders
Littero keeps every progesterone result on a chart next to the heat calendar, and turns the right date into a whelping window, so each female’s cycle is clear at a glance.
- Heat cycles and progesterone charts
- Mating-to-whelping date ranges
- Reminders for tests, vet visits and whelping
