The un-spayed female dog comes into heat about every six or seven months. This means she will have one or two cycles a year, with each one lasting an average of twenty-one days. The age at which the bitch has her first heat varies, but it is usually about six months old. Larger dogs take longer to mature so it is not uncommon for them to have their first heat at 18 months, sometimes even older.
 
There are three different stages in the cycle. The first stage is called ‘pro-oestrous.’ This is when you may notice bleeding or spotting from the vulva. Her vulva may also be swollen and she might be urinating more often than usual. Every dog in the neighbourhood will be loitering with intent but she will not stand to be mated, however this does not mean she can’t get pregnant. Around this time she may show signs of restlessness and have the tendency to roam. This stage lasts around seven to ten days. For bitches coming into heat for the first time it is common for this stage to only last a few days.

The second stage is known as ‘oestrous.’ This is the receptive period meaning she will stand to be mated and is most likely to get pregnant during this time. It starts about ten days after the spotting/bleeding starts and lasts around nine days. By now the bloody discharge is changing to a pink, straw like colour. She may roam to find a mate so if you don’t want puppies keep her locked up during oestrous.

The third stage is called ‘dioestrus’ which means the bitch is now coming out of heat. This lasts for approximately two to three months. She will not allow mating during this time. Dioestrous leads into ‘anoestrous’ which is the time where her sex hormones are at their lowest and she is out of heat. This stage lasts around four to five months before she begins her next cycle.

Bitches intended for breeding should not be mated until their second or third heat at around eighteen months.
If you do not plan on breeding with your female dog it is a great idea to get her spayed. We do this around six months of age, usually before the first heat. If she has had a heat it is best to wait two weeks after it has finished before we spay her. Spaying rules out any unwanted pregnancies, uterine infections and reduces the risk of mammary cancer later on in life.