Understanding the Canine Reproductive Cycle

Many breeding failures don’t come down to bad luck — they come down to a poor understanding of the canine reproductive cycle.

Relying on dates, behaviour alone, or “what worked last time” is one of the most common reasons breeders miss fertile windows, mistime matings, or misinterpret pregnancy signs.

A bitch’s cycle is hormonally driven, not calendar driven. If you don’t understand the stages properly, everything that follows — cytology, mating, scanning, and whelping — is built on guesswork.

The Four Stages of the Canine Reproductive Cycle

1. Proestrus

This is the stage most people recognise as “she’s in season”.

• Vulva swelling begins

• Bloody discharge is usually present

• Males are attracted

• The bitch is not ready to mate

Hormone activity is increasing, but ovulation has not occurred. Mating during proestrus is poorly timed and often unsuccessful.

2. Oestrus

This is the fertile stage — and the one breeders must get right.

• Discharge often lightens or becomes straw-coloured

• Vulva softens and may wrinkle

• Flagging behaviour may be seen

• Ovulation occurs early in this stage

Crucially, ovulation does not mean immediate fertility. Eggs still need time to mature before they can be fertilised. This is where timing errors happen most often.

3. Diestrus

Whether pregnant or not, hormonally this stage looks the same.

• Progesterone remains high

• Pregnancy signs can be misleading

• False pregnancy commonly occurs

This is why scanning too early or relying on behaviour alone causes confusion.

4. Anoestrus

This is the rest phase.

• Hormones are low

• The reproductive tract recovers

• The body prepares for the next cycle

Skipping proper recovery or breeding too frequently compromises long-term reproductive health.

Why This Matters

If you don’t know where a bitch truly is in her cycle:

• Cytology results will be misread

• Ovulation timing will be off

• Matings may be mistimed

• Pregnancy expectations become unreliable

Understanding the cycle is the foundation of responsible breeding — everything else builds on it.

#ProPetTraining

#CanineReproduction

#ResponsibleBreeding

#DogBreedersUK

#CanineEducation

#DogBreedingEducation

#CanineFertility

#DogHeatCycle

#BreedingBetterDogs

#CanineHealth

#EthicalBreeding

#BreederEducation

#DogWelfare

#CanineHormones

#ProfessionalBreeders