What does "estrus" signify in a dog's reproductive cycle?

Estrus signifies the stage of ovulation in a dog's reproductive cycle. This phase is characterized by the female dog being fertile and receptive to mating. During estrus, the ovaries release eggs, and the female exhibits behavioral changes that indicate she is ready to breed.

Understanding estrus is important for breeding management since it is the optimum time for insemination to achieve pregnancy. The duration of estrus can vary, but it typically lasts about 5 to 14 days within the entire reproductive cycle, which includes other phases, such as proestrus and diestrus.

The other options relate to different aspects of a dog's life. The entire cycle duration encompasses all phases, not just estrus. Days of lactation pertain to the period after giving birth, and the growth phase refers to the developmental stages of a puppy before reaching maturity. Therefore, recognizing estrus as the specific phase where ovulation occurs is key in understanding canine reproduction.