Reproductive Health & Neutering
Stages of the reproductive cycle
Four stages describe the cycle; they cannot be identified reliably from a calendar alone.
Timing is approximate
The table gives broad clinical context. Behaviour and discharge overlap between stages. Veterinary examination and tests may be needed to establish the stage. This is not a mating planner.
| Stage | Approximate duration, not a fertility rule | What changes |
|---|---|---|
| Proestrus | Often around 9 days; about 2 days–3 weeks | Oestrogen rises; vulva swells, discharge may be bloody; males show interest, female usually not receptive. |
| Oestrus | Often around 9 days; about 3 days–3 weeks | Ovulation occurs; she may accept mating; discharge can lighten or continue. Signs do not define fertility. |
| Dioestrus | Roughly 2 months in a non-pregnant dog | Progesterone remains elevated then falls, whether or not she is pregnant; visible season signs settle. False pregnancy may appear. |
| Anoestrus | Several months; commonly about 1–6 months | Reproductive resting phase with low hormone activity; the uterus recovers before another cycle. |
Do not predict fertile days
A tracker cannot determine fertility, establish a safe mating date or replace veterinary assessment. Do not use bleeding, its cessation or calendar estimates to decide that mating is safe.
Choose a short guide
Evidence and review
About this guidanceReview details and sources
Evidence and review
Evidence assessed 8 October 2026. General owner information, not diagnosis or individual treatment. Practical care suggestions are editorial guidance. Independent veterinary and native-language review has not been obtained. References do not imply endorsement. Existing linked pages retain their own evidence-review dates.