Introduction

Ovarian cycles are from oestrus to oestrus. Oestrus is the easily identifiable external marker.

Classification of Oestrous Cycles

The phase immediately preceding oestrus.
Marked increase in reproductive activity.
Follicular growth and regression of the corpus luteum of the previous cycle (in polyoestrous species).
Uterus enlarges slightly
Endometrium becomes congested and oedematous, glands show secretory activity.
Vaginal mucous becomes hyperaemic.
- Increase in cell numbers in the vaginal epithelium.
- Superficial layers become cornified.
The bitch shows external evidence:
- Vulval oedema
- Hyperaemia
- Sanguinous vulval discharge