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Companion Animal Practice
Assessment of optimal mating time in the bitch
  1. Denise Hewitt

    Denise Hewitt graduiated from Leeds University in 1990 with a zoology degree. She worked as an embryologist at King's College Hospital Assisted Conception Unit before undertaking a PhD in canine reproduction at the Royal Veterinary College. She is currently a postdoctoral research fellow supported by the Guide Dogs for the Blind Association within the RVC's unit of veterinary reproduction.

  2. Gary England

    Gary England graduated from the Royal Veterinary College in 1986. He was surgery house surgeon at the Beaumont Animals' Hospital before spending a short time in practice and then undertaking a PhD in canine reproduction. He is now professor of veterinary reproduction at the RVC.


THE bitch is described as being monoestrus, which means that a long period of anoestrus occurs between successive periods of oestrus, whether she becomes pregnant or not. Correct monitoring and timing of the cycle is, therefore, essential if a fertile mating is to be achieved, since the next opportunity will not occur for some time. An important consideration when attempting to achieve a successful mating is the variation which occurs both between bitches and between cycles in the same bitch in the timing of ovulation in relation to the onset of proestrus. Despite this, many breeders continue to time matings using a standard number of days from the start of vulval bleeding (onset of proestrus). Bitches are, therefore, often mated at an unsuitable time, resulting in an apparent, and usually avoidable, infertility. Correct timing relies on the detection of physiological changes that occur between the onset of proestrus and oestrus. As discussed in this article, there are several different techniques which may be employed to assess the optimal time for mating, including measurement of plasma hormone concentrations, examination of exfoliated vaginal cells, and vaginal endoscopy.

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