How do I confirm feline oestrus and ovulation?

Behavioural signs (vocalising, lordosis, treading) plus vaginal cytology confirm oestrus — the fully cornified (keratinised) smear marks the receptive window. Ovulation itself is confirmed retrospectively, typically by progesterone rising above ~2 ng/mL 24–48 hours after mating, or by pregnancy.

Why does feline breeding fail so often?

Because queens are mated at the wrong point in the follicular phase, or the male is introduced before the queen is fully in oestrus. Since ovulation depends on adequate mating stimulation, a poorly timed or insufficient mating means no ovulation — and no pregnancy regardless of sperm quality.

What does a breeder actually need to test?

Vaginal cytology to time introduction, progesterone only to retrospectively confirm ovulation, and then relaxin or ultrasound to confirm pregnancy. The testing burden is lighter than canine breeding, but the timing discipline around oestrus is even more critical.

Feline Breeding & Ovulation: Why Cat Testing Is Different

Q: Are cats induced ovulators?

Yes — unlike dogs, which ovulate on a fixed cycle, queens ovulate only in response to mating (or hormonal induction). The physical stimulation of mating triggers an LH surge, and ovulation follows roughly 24–48 hours later. This is why the canine progesterone-timing protocol has no feline equivalent.

Q: Can I use progesterone to time feline breeding?

No. In dogs, progesterone maps the pre-ovulatory rise and defines a breeding window; in cats, that window does not exist because ovulation is event-triggered, not cyclical. Applying the canine 8–15 ng/mL protocol to a queen is a category error that misses the biology entirely.

Q: How is feline pregnancy confirmed?

Two reliable methods: ultrasound (detectable from around day 15–18 post-ovulation) and a relaxin blood test (reliable from about day 20–30). Relaxin is produced by the placenta, so a positive confirms a real pregnancy and distinguishes it from pseudopregnancy.

TL;DR — The single most important fact in feline reproduction is that queens are induced ovulators: they do not ovulate on a cycle like bitches — ovulation is triggered by the physical stimulation of mating. So the canine progesterone-timing protocol, with its 8–15 ng/mL breeding window, simply has no feline equivalent, and anyone who transplants it is making a category error. Feline breeding testing is actually lighter: vaginal cytology times the introduction, progesterone is used only retrospectively to confirm ovulation (rising above ~2 ng/mL 24–48 h after mating), and relaxin or ultrasound confirms pregnancy. The discipline that matters is not serial hormone curves — it is getting the queen properly mated at the right point in oestrus.

In Plain Terms

A bitch ovulates on a clock; a queen ovulates on a trigger. The dog releases eggs whether or not she is mated, which is why dog breeders watch progesterone like a countdown timer. The cat holds her eggs until mating actually happens — no mating, no ovulation, no pregnancy. That one difference rewrites the entire testing playbook.

The Biology That Changes Everything

	Bitch (dog)	Queen (cat)
Ovulation	Spontaneous, on cycle	Induced by mating
Trigger	Hormonal (LH surge)	Physical stimulation of mating
Timing after trigger	LH → ovulation ~2 days	Mating → ovulation ~24–48 h
Progesterone’s role	Times the breeding window	Confirms ovulation retrospectively
Breeding window	8–15 ng/mL	None — event-driven

The practical consequence: in the dog, you test to decide when to breed. In the cat, you test to confirm oestrus and confirm that ovulation happened — a fundamentally different question.

Step 1 — Confirm Oestrus (Vaginal Cytology)

The one test that genuinely drives feline breeding is vaginal cytology. A fully cornified (keratinised) smear — where essentially all the epithelial cells are anucleate squames — marks the receptive window when the queen will accept the male. It is the feline analogue of the dog’s progesterone curve, but it answers “is she ready?” rather than “what hour should I breed?”

Behavioural signs (vocalising, lordosis, treading the hind legs, tail deflection) are the cheap first signal, but cytology is the objective confirmation. Relying on behaviour alone is how a shy or silent queen gets mated too early.

Step 2 — Retrospective Ovulation Confirmation (Progesterone)

Here is the subtlety: you cannot time feline ovulation with progesterone, but you can confirm it happened. A progesterone that rises above ~2 ng/mL in the 24–48 hours after mating is evidence that ovulation occurred.

Why this matters: if the mating was poorly timed or insufficiently stimulating, the queen may not ovulate at all. A post-mating progesterone that stays flat is your early warning that the cycle failed — before you wait weeks to discover she is not pregnant.

Step 3 — Confirm Pregnancy (Relaxin or Ultrasound)

Two reliable options:

Ultrasound — fetal structures visible from around day 15–18 post-ovulation.
Relaxin — the pregnancy-only hormone, reliably detectable from about day 20–30. Because relaxin comes from the placenta, a positive confirms a real pregnancy and cleanly rules out pseudopregnancy.

The same relaxin logic as dogs applies: do not test too early (before ~day 20 there is no placenta to produce it), and one confirmatory test around day 25–30 is usually enough.

Why Feline Breeding Fails

The failure mode is rarely the testing — it is the mating. Because ovulation depends on adequate stimulation, a queen introduced to the male too early (before full oestrus) or mated too briefly may simply not ovulate. The result is a “failed breeding” that was never a sperm problem at all.

This is the counterintuitive takeaway for anyone coming from canine breeding: in cats, the timing of the mating matters more than the hormone number. Spend your effort on getting the queen properly mated at peak oestrus, and use progesterone/relaxin to verify, not to steer.

How the Test Runs

Confirm oestrus by behaviour plus a fully cornified vaginal smear.
Introduce the male during the receptive window; allow multiple matings.
Optionally check progesterone 24–48 h post-mating — a rise above ~2 ng/mL confirms ovulation.
Confirm pregnancy by ultrasound (~day 15–18) or relaxin (~day 20–30).

Related products: Canine Progesterone Test · Canine Relaxin Test · FIA680 Analyzer

FAQ

Are cats induced ovulators?

Yes — mating triggers the LH surge, and ovulation follows ~24–48 hours later. The dog’s cyclical, progesterone-timed protocol has no feline equivalent.

Can I use progesterone to time feline breeding?

No — the feline “window” does not exist because ovulation is event-triggered. Applying the canine 8–15 ng/mL protocol to a queen is a category error.

How do I confirm oestrus and ovulation?

Vaginal cytology (fully cornified smear) confirms oestrus; progesterone rising above ~2 ng/mL 24–48 h post-mating confirms ovulation retrospectively.

How is feline pregnancy confirmed?

Ultrasound from ~day 15–18, or a relaxin test from ~day 20–30. Relaxin is placental, so a positive confirms a real pregnancy.

Why does feline breeding fail?

Poorly timed or insufficient mating — no adequate stimulation, no ovulation (which follows 24–48 h after mating), no pregnancy, regardless of sperm quality.

What does a breeder actually test?

Vaginal cytology to time the introduction, progesterone to confirm ovulation (>2 ng/mL), then relaxin (~day 20–30) or ultrasound to confirm pregnancy. Lighter than canine breeding, but timing is more critical.

Key Takeaways

Induced ovulation rewrites the protocol — queens ovulate only after mating (~24–48 h later), so the canine progesterone countdown does not transfer.
Cytology, not progesterone, times the breeding — a fully cornified smear marks receptivity; progesterone is only retrospective (ovulation confirmed above ~2 ng/mL).
Progesterone >~2 ng/mL post-mating confirms ovulation — a flat value is an early warning the cycle failed before you wait weeks.
Confirm with relaxin (~day 20–30) or ultrasound (~day 15–18) — both are reliable; relaxin cleanly rules out pseudopregnancy.
The mating, not the number, is the failure point — get the queen properly mated at peak oestrus (ovulation follows 24–48 h), then use tests to verify, not steer.

References

Root Kustritz MV. Feline reproduction and breeding management. Vet Clin North Am Small Anim Pract.
Little SE. The Cat: Clinical Medicine and Management. Elsevier.
Buff S, et al. Relaxin for early feline pregnancy confirmation.

This content is for educational and product-selection purposes only. It is not a substitute for veterinary guidance — work with a theriogenologist for feline breeding. Product specifications are as published by Migibio (Guangzhou Magic Biotech Co., Ltd.) and may change.