Oestrous Cycle - Cat

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Oestrous Cycle

  • Seasonally polyoestrous
  • Long day breeders with a period of anoestrus beginning in late autumn.
  • Increasing daylight is the most important factor for inducing the resumption of reproductive activity. The first oestrus will usually occur soon after the shortest day of the year.
  • If constant 14 hours of daylight is provided, the queen will continue to cycle all year round.
  • Some non-pedigrees have regular oestrous cycles lasting about 3 weeks, but others show no regular pattern.
  • Duration of oestrus is 7-10 days regardless of mating.

  • Oestrogen concentrations increase dramatically at the time of oestrus and may double over 24 hours.
  • The principle oestrogen is Oestradiol 17β.
  • The rise in Oestradiol 17β corresponds with behavioural oestrus, there are no external signs of pro-oestrus.

Mating and Ovulation

  • The queen is an induced ovulator, so mating is important in triggering ovulation.
  • There are receptors in the vulva, which are stimualated by copulation.
  • This results in release of LH fromt he anterior pituitary gland.
  • Only 50% of queens ovulate after a single mating, because multiple ovulations are usually required for adequate LH release.
  • The ovulatory LH surge begins within minutes of coitus.
  • LH peaks within 2 hours, then returns to basal levels within 8 hours.
  • Further matings before the peak in LH will result in further LH release.
  • After multiple matings over 4 hours or more, further matings will not result in any further LH release.
    • Due to depletion of the pituitary pool of LH, or the pituitary becoming refractory to further GnRH stimulation.
  • Once significant quantities of LH are reached, all ripe follicles will rupture (all or nothing response).
  • Occasionally, ovulation will occur in the absence of contact with an entire tom.
    • Receptors similar to those in the vulva are found in the lumbar area.
    • These can be stimulated if the queen is mounted by other females or castrated cats.


  • Sterile matings induce ovulation and result in pseudopregnancy.
  • Progesterone concentrations are similar to those of pregnancy for the first 3 weeks.
  • After this, progesterone levels gradually fall and reach baseline at 7 weeks.
  • Oestrus will occur shortly afterwards.
  • Nesting behaviour and lactation are rarely seen, but hyperaemia of the nipples is as evident as in pregnancy.
  • Appetite may increase, and fat may distribute to create an increased abdominal size.