Birth Control in the Female Dog/Cat

How can I prevent my pet from coming into oestrus and having puppies?

  • Surgery - ovariohysterectomy - spaying
  • Medical management using hormonal drugs


Spaying involves the removal of the womb and ovaries. It is permanent and irreversible. Although involving major surgery with general anaesthesia the risk is minimal in the healthy animal particularly if she is immature.

Is it necessary to remove the ovaries? This is not done when a woman is sterilised.

The reproductive cycle of the dog or cat is entirely different from that of woman. Female cats can come into season up to 6-8 times a year. The object of ovariohysterectomy is to ensure that cycling does not take place so that the pet does not show signs of heat (oestrus) and consequently is not bothered by other dogs/cats and cannot become pregnant.

Are there any other advantages?

False pregnancy

Spaying your bitch will ensure that she does not have problems of false pregnancy. This can sometimes be troublesome after a season.


This is an inflammation of the womb which can also occur following a season, particularly in bitches that have not had puppies. Once her uterus has been removed at ovariohysterectomy this risk is removed.

Mammary neoplasia

If the operation is performed before she is mature the chances of developing breast cancer later in life are much reduced.

Medical control of oestrus

Tablets and injections are available containing broadly similar hormonal drugs to those used in the human contraceptive pill. These are effective but are not permanent. They can be used to postpone or suppress your bitch's season and once administration has ceased your bitch will start to come into season again and can be successfully mated.

Do these drugs have any side effects?

Depending on the formulation they can sometimes cause an increase in appetite with concomitant obesity and occasionally precipitate other medical problems such as diabetes. Long term or continuous administration is not recommended because this increases the possibility of side effects. These methods are useful when going on holiday, attending a show etc. if your pet is likely to come into season at that time.

Do they effectively suppress the signs of heat?

Yes, with correct dosage administration will prevent the signs of heat which can be postponed and suppressed entirely. Ovulation will not occur and the bitch cannot become pregnant.

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