Oestrus Behaviour - Anatomy & Physiology

Mare

• Oestrous detection is a problem because mares not in oestrus can cause significant damage to a stallion.
• May be a slight oedema of the vulva and a mucoid discharge.
• Generally mares return to oestrous about 6-10 days after foaling.
  • Called a 'foal heat' because often the foal develops diarrhoea at this time, which makes the oestrus easy to detect.
    • Fertility may not be high at 'foal heat' oestrus.
• Mares with an older foal at foot may not show signs of oestrus, as they are protective of the foal ('foal shy').

• Commonly teasing is performed (usually daily) using a less valuable stallion over a 'teasing board'.
• Mare will stand as if to urinate, lift her tail and lean her hidquarters toward the stallion.
• Mare repeatedly exposes her clitoris ('winking')
• If the mare is in oestrus, the stallion usually demonstrates a Flehmen response.

Clinical Methods and Assessments for Oestrus Detection

• Detection of a follicle and absence of a corpus luteum by palpation or ultrasound examination of ovaries.

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Bitch

• Long period of proestrus where the bitch is attractive, but will not allow mating.
  • Characterized by:
    • Vulval swelling
    • Presence of serosanguinous discharge

• Followed by standing oestrus:
  • Standing to be mated
  • Deviation of the tail
  • Discharge becomes paler in colour
  • Reduction in vulval oedema

• Poor relationship between time of ovulation and external appearance.

Clinical Methods and Assessments for Oestrus Detection

• Assessment of vulval softening
• Assessment of vaginal epithelial cells
• Examination of the appearance of the vaginal wall.
• Measurement of plasma progesterone concentration (detecting a rise in progesterone that preceeds ovulation in this species).

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Queen

• Oestrus detection is important, for although the queen is an induced ovulator (thus ovulation will not be missed, the LH response to mating decreases with each day of oestrus and [[follicles ultimately regress.
• Proestrus is short and often unnoticed.
• Oestrus is characterized by increased vocalization,rubbing and rolling.
• Queen is more active and will seek the tom.
• Stands to be mated by lowering her front quarters and extending her hind legs.
• Demonstrates lordosis
• Tail erect and held to one side.
• Slight mucoid vulval discharge.