What happens during a female dog's heat cycle? - briefly
A female dog's heat cycle, also known as estrus, is characterized by several distinct phases: proestrus, estrus, and diestrus. During this cycle, hormonal changes prepare her body for mating and potential pregnancy. Proestrus is marked by vaginal discharge and swelling of the vulva, while estrus is the fertile period when she may accept a male dog for mating. Diestrus follows, during which any fertilized eggs implant in the uterus or are shed if not fertilized.
What happens during a female dog's heat cycle? - in detail
The estrous, or heat, cycle in female dogs is a complex process governed by hormonal changes. It typically occurs twice a year and consists of four distinct phases: proestrus, estrus, diestrus, and anestrus.
During proestrus, which lasts about 9 days, the dog's body prepares for ovulation. The first visible sign is a bloody vaginal discharge, indicating that the follicles in the ovaries are maturing. This phase also sees an increase in estrogen levels, leading to behavioral changes such as increased urination and attractiveness to male dogs.
Estrus, or heat proper, begins when the dog is most fertile and lasts around 9 days. During this time, the vulva swells, and the discharge becomes more watery and straw-colored. The dog may display overt signs of wanting to mate, such as flagging her tail to one side while standing with her hind legs slightly spread. Ovulation usually occurs midway through estrus, around day 3 or 4, and the eggs are viable for about 4 days.
Diestrus, the luteal phase, follows estrus and can last anywhere from 60 to 90 days. During this period, the corpus luteum forms in the ovary, producing progesterone to maintain the pregnancy if fertilization has occurred. If the dog is not pregnant, the corpus luteum will regress, leading to a decrease in hormone levels and the onset of anestrus.
Anestrus, or the period of sexual quiescence, lasts about 4-5 months until the cycle begins again. During this phase, there is little or no activity in the reproductive system. The dog's behavior returns to normal, and she exhibits no signs of being in heat.
Throughout the estrous cycle, proper care and monitoring are essential to ensure the health and well-being of the female dog. This includes preventing unwanted pregnancies by keeping the dog away from male dogs during heat and providing a clean environment to minimize the risk of infection.