Stage 4 – Anestrus
Anestrus is a non-fertile stage, usually lasting between seven to nine months until the female comes into heat again.
When will my female go into her first heat? Age of first heat cycle
The first Heat cycle can start as soon as six months of age. However, every dog is different also in this regard, and some do not get into their first heat cycle before the age of 18 months. It is said that in general small dogs come into heat sooner than larger breeds.
Frequency of heat cycles
The average female dog goes into heat about every seven to nine months (Anestrus) after the last cycle ended.
However, the time period can range even more in some individuals.
There will always be some dogs going into heat before 7 months or after more than 9 months, but it would not be accurate to call that occurrence “average.”
The last is more close to my own experience with Mila so far. Her first cycle came at the age of nine months, the next one came seven months later and the third one came ten months after the last one. For now I don’t see any regularity in that. My best bet is to keep track of her heat cycles and watch out for the typical signs.
Signs of the heat cycle
Many dogs keep themselves very clean and it can become hard to tell whether they are in heat at all.
Bull Terriers usually do not reach the affected areas very well. Therefore it is usually a little easier to notice bloody discharge, once it occurs.
Just as the mood can vary in humans with hormonal fluctuations, dogs can get moody too. Female dogs often become a little more cuddly and sensitive right before getting into and during their heat cycle.