Many owners that have female pets do not keep track of the estrous cycles and they do not pay the necessary attention to it.
The most common comment is “I do not have more pets at home so I do not really care, she will at some point enter in heat”.
Being in heat causes hormonal changes, which, in many cases comes with changes in the character. These changes typically come few weeks before being in heat, and sometimes continue even a week after.
In female puppies that enter in heat for the first time, few weeks before could dirt at home, i.e. they break their relief habits. In addition, it is common for them to urinate more frequently. If there are more than one female dogs at home, it is not unlikely for them to synchronize their biologic estrous. Regarding diseases, it is important to inform the veterinarian in case there are important deviations from the typical time between heat periods.
Concluding, knowing when our pet will be in heat helps us understand better their behavior and justify some of the things they do.