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Lecture Notes

The estrous cycle in dogs varies tremendously depending on breed as well as size of the animal.

The estrous cycle may begin as early as six months old in some smaller breeds and as late as 18 months in some of the larger breeds.

The duration of the estrous cycle in one particular dog is fairly consistent over time; but again, there's a great deal of variability among individuals and among breeds. To cycle once every seven months is a very rough average among dogs. Some breeds will have a tendency to cycle once every four months (for example, the German Shepherd) while others, such as the Basenji will tend to cycle once every 12 months.