Bitches are all individuals and although their body goes through the same changes when entire (unneutered) and experience a season (heat), they may not all cycle in the same way or have the same experience with each season. Here are a few common differences that some bitches may experience during their cycle.
Length of Cycles
The length of a cycle from one season to the next can vary between breeds, each bitch and each season. For example a bitch can start to season at any age but the most common time for maturity and a first season is approximately 5-12 months of age. A bitch may have long cycles which may be a year between each season (heat), a short cycle of 4 months between each season, or a varied cycled no established timing between cycles which can be harder to predict.
Split Season
A split season may also be known as a split heat and can be very confusing for the owner when it occurs, as your bitch will show many signs of coming into season which can be very convincing, but then all the symptoms disappear and it will all start over again a few weeks later with a full season. The split season occurs because for whatever reason the bitch did not have enough hormones to bring her into a full season. This can be seen in first and consecutive seasons, also a bitch may only have this once on her cycle but it may happen with later seasons or even every season.
Light or Shallow Season
A light or shallow season may occur in any season whether it’s a bitches first or subsequent seasons. It is basically a lighter bleeding, possibly less swelling and seems to come and go rather quickly at times. Some bitches may have a light season for their first season only or have a few light seasons as their cycle develops but some bitches just have them with every season and are lighter bleeders than other bitches. It is still a full season with all the hormones and changes of a regular season, but it may seem to be lighter to humans when looking for symptoms and signs.
Colourless Season
A colourless season can be difficult to see in some bitches as the bitch will have no bleeding or blood loss at all, hence the name colourless season. She may be swollen which is an indicator shes in season and her mood may change. She can still attract males and be mated to produce puppies, but she will not have any blood lose which can make timing difficult for some owners or breeders. It may also be more difficult to notice the start and end of the season when a bitch experiences a colourless season.
Dry Season
This is similar to a colourless season but without the swelling so there really is minimal signs when a bitch has a dry season. The bitch may change in behaviour and may attract male and show signs of flirting around her optimum mating time but a dry season is hard to predict and difficult for some owners to notice. This may be more common in certain breeds which makes breeding and expanding the breed further more difficult.
Prolonged Season
A prolonged season may be seen on any season which basically means the bitch can bleed for longer or be swollen for longer than expected, and although each bitch is an individual there is always a possibility that one season will be 3 weeks from start to finish and the next may last almost 5 weeks with more bleeding and swelling.
Phantom Pregnancy
Phantom pregnancies are also known as false pregnancies and are very common in entire bitches as a bitches hormones go through the same changes whether they are pregnant or not. A phantom pregnant may occur but be unnoticed by owners as the signs are not effecting their bitch but in some cases the changes of a phantom pregnancy are quite alarming for owners as a bitch can act very differently, be withdrawn, be less active, display nesting behaviour and generally show all the signs and symptoms of being pregnant without actually being pregnant. It is the severity of the phantom pregnancy that is the concern rather than the hormonal changes that every bitch naturally goes through, and a bitch suffering a realistic phantom pregnancy can be upsetting to some owners if their bitch is withdrawn or acting unusual. A phantom pregnancy can happen on a first season or later seasons, and a bitch may suffer from a phantom pregnancy each season. If a bitch experiences a very realistic and concerning phantom pregnancy some vets will recommend spaying as the next season may bring on another phantom pregnancy with even more realistic symptoms. A vet may also prescribe medication or give a hormone injection to help if your bitches is having a worrying phantom pregnancy.