Dog - Heat or Oestrus

The reproductive cycle in the bitch

Most bitches come into heat (oestrus) approximately every six months and this can be a problem unless you have her neutered.

All unneutered bitches come into heat (oestrus) on a regular basis every 4–14 months depending on the size and breed. Toy dogs and small breeds tend to mature earlier and cycle more frequently than the giant breeds.

When in heat the bitch will sometimes have a copious blood coloured discharge for at least part of her heat period. She will also be attractive to male dogs which can be a problem if she has to be exercised in public open spaces.

How will I know when my bitch is coming into season?

The season, heat or oestrus is divided into three parts: pro-oestrus, oestrus (which is when the bitch will accept mating) and met-oestrus. Each phase lasts approximately a week to ten days so in total the bitch will be in heat for about three weeks.

• Pro-oestrus. This starts with swelling of the vulva and a blood stained discharge which sometimes can be very copious. Some bitches spend their entire time cleaning themselves so you scarcely see any discharge. During pro-oestrus the bitch becomes attractive to male dogs although she is unlikely to allow mating at this stage, nevertheless it can sometimes be difficult exercising her in a public park etc. When in oestrus it often appears that your bitch is passing small quantities of urine frequently. This contains certain marker scents (female pheromones) and it is her method of advertising the fact that she will soon be ready for suitors!
• Oestrus. After about 7–10 days oestrus proper occurs. During this time she is ready for mating. During oestrus the vulva remains swollen but the discharge becomes colourless and reduces in volume. During oestrus ovulation occurs. If mated she is likely to become pregnant.
• Met-oestrus. This is the third and final stage of the season. The swelling of the vulva gradually reduces, discharge ceases and she is no longer attractive to male dogs. Most bitches come into heat about every six months but bear in mind, as mentioned earlier, that this can vary from 4-18 months depending on the size and/or breed.

How do I exercise her when she is in season?

When on heat your bitch is not ill and consequently requires exercise. If this is only available in public areas frequented by other dogs it can be a problem since some bitches ovulate early and thus allow mating at the beginning of their season (i.e. in pro-oestrus). In any case the attention of other dogs is in itself usually a problem.

If you do not wish to neuter your pet either surgically or by medical means, it is important that you change the exercise pattern and select times and places when male dogs are less likely to be around.

If there is any likelihood of other dogs being in the vicinity exercise should be on a lead.
Extending leads are very useful at this time!

What about odour suppressants?

Odour suppressants that are applied to the hair around the tail and hindquarters work in some cases but they can be of limited efficacy.

Similarly tablets containing chlorophyll are also available which are claimed to reduce the bitch’s attractive scent when on heat. They too appear to be of limited use in many cases. However these products are unlikely to harm your dog even if they do not work, so try them. You may be lucky.

Is my bitch likely to have any other problems associated with her cycle?

• False or phantom pregnancy: Even though they have not been mated some bitches behave as though they are pregnant. The bitch goes off her food (although few lose weight!) In most bitches the symptoms are mild and should be ignored. Encourage normal exercise and discourage any nesting behaviour, mothering of toys etc. In some cases false pregnancy (pseudocyesis) can be very severe and the bitch may appear generally unwell with enlargement of breasts and production of milk. Some bitches will make a nest which they are disinclined to leave, guarding toys and other objects. Sometimes temperament changes are noted. If you have any concerns please contact us since treatment may be necessary.
• Pyometra: Some bitches suffer severe enlargement of the uterus following a season. This may be infected and the bitch can show signs of increased thirst, enlarged abdomen and severe, life-threatening illness. Sometimes the condition is not responsive to medical treatment and ovariohysterectomy (spaying) has to be carried out. See handout on Pyometra.
• Breast cancer: Entire bitches are considerably more prone to mammary neoplasia, (breast cancer) than those that have been neutered at a young age. The first signs are usually hard enlarging lumps within the breast tissue. Please contact us if you are at all worried.

Since I have experienced the problems you describe when my bitch is in heat, should I have her spayed?

Spaying has few disadvantages and many advantages. Please see handout on Spaying. We will be happy to discuss this with you.