Reproductive Cycle


The cycle of female dogs is said to be non-seasonal.  They can come into heat at any time during the year.  This usually happens every 6-7 months, but can be dependent on the breed...
The cycle is divided into four stages:
  • Pro-oestrus
  • Oestrus, which involves the hormone oestrogen
  • Metoestrus, which involves the hormones progesterone and prolactin
  • Anoestrus, a quiet period with no hormonal influence


Typically the bitch's vulva will swell and produce a blood tinged vaginal discharge   At this time she will attract the male but will not stand to mate.  This lasts around 7 - 10 days.


This is when she will accept the male and stand to mate, ovulation occurs 2 days into the cycle whether she is mated or not.  This lasts for around 7 - 10 days.



Metoestrus, which lasts around 90 days, is associated with the following hormones:
  • Progesterone - maintains pregnancy
  • Prolactin - causes milk production and nursing behaviour in late pregnancy, in preparation for the arrival of puppies
High levels of progesterone and prolactin are still produced even if she is not pregnant and it is these high levels of prolactin that are responsible for causing false pregnancy.


The final part of the bitches reproductive cycle is referred to as anoestrous. This usually lasts for around 4-5 months, but can be variable.

During this stage levels of the three hormones - progesterone, oestrogen and prolactin - decrease to normal levels.

The functions of the hormones

Each of the reproductive hormones have their own function in the bitches cycle and are summarised as follows:

This is referred to as a steroid hormone.   It is secreted by the corpus luteum, (an area of the ovary that secretes hormones) of the ovary that maintains pregnancy.  It also promotes the development of the mammary glands.

Another steroid hormone, this is produced primarily by the ovaries.   It stimulates changes in the female reproductive organs during the oestrous cycle and promotes the development of secondary sexual characteristics.

This hormone is released from the pituitary gland, (the master hormone producing gland).  It stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation.

We would advise that you keep a record of all your bitch's season dates.  This will help us with gathering her medical history if she were to encounter problems relating to her reproductive health.  

If your bitch is not being bred from we will, in most cases, recommend neutering.  This may be from 6 months of age before the onset of the bitch's season, but other factors such as breed type, temperament and general behaviour need to be discussed before a decision of when to neuter is made.    For the health of your bitch we do not neuter her if she is in season, but wait until 3 months after her last season.  Equally if your dog is experiencing a phantom or false pregnancy she will need treatment before neutering.  

If you are concerned about your bitch's health or want to find out more about neutering, please ring us on 01376 325511.

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