Dog Copulatory Behaviour - Anatomy & Physiology

First Stage Coitus - The Tie

• Bitch in Oestrus spots bloody fluid just before the receptive stage.
• Male identifies the female.
  • Dogs are very aware of a bitch in oestrus and can detect them from 500-600 meters away.
• Bitch adopts receptive posture ('stands') with the tail deviated to one side ('flagging').
• Dog mounts and thrusts to achieve intromission.
  • Intromission with a partially erect penis aided by the Os Penis
• Vulval erectile tissue of the bitch grips the bulbus glandis of the penis.
• Penis achieves full erection (the 'Tie')
• Lasts 1-2 minutes
• First and second fractions of semen are ejaculated.

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The Turn

• Shortly after ejaculation, the dog dismounts and turns around while lifting one hind leg over the bitch.
• The male and female remain 'tied' because the bulbus glandis of the penis remains engorged with blood.
• Contractions of muscles near the base of the penis prevent venous outflow of blood from the bulbus glandis.
• Sphincter muscles of the vulva constrict
  • Compresses dorsal veins of the penis.
  • Prevents venous outflow.

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Second Stage Coitus

• After the turn,they stand with their hind quarters in contact and their heads facing opposite directions.
• Third fraction of semen is ejaculated.
• Lasts 5-45 minutes
• Encourages uterine rather than vaginal insemination.
• Dog steadily ejaculates up to 30ml seminal fluid.
  • Delivered through the Cervix to the Uterus.
  • Forces the sperm-rich fraction into the Uterus.

• Dog then turns to face the opposite direction (the 'Turn')
• Ejaculation