What happens to dogs during heat? - briefly
During the heat cycle, female dogs experience hormonal changes that prepare their bodies for pregnancy. This period is marked by physical and behavioral changes, including swelling of the vulva, increased urination to mark territory, and attracting male dogs.
What happens to dogs during heat? - in detail
During estrus, commonly referred to as "heat," female dogs undergo significant hormonal and physiological changes. The process begins with the release of luteinizing hormone (LH) from the pituitary gland, which in turn triggers the ovaries to produce estrogen. This increase in estrogen levels stimulates the development of the uterine lining, preparing it for potential implantation of fertilized eggs.
One of the most noticeable changes is the swelling of the vulva, which becomes more prominent and may exude a bloody or straw-colored discharge. This phase is known as proestrus and typically lasts around 9 days. During this time, male dogs are strongly attracted to the female's scent, but mating attempts are usually refused by the female.
As estrogen levels peak, they trigger a surge in LH, leading to ovulation. This occurs about 5-10 days after the onset of proestrus and marks the transition into the estrus phase, which lasts approximately 9 days. During estrus, the female becomes receptive to mating and will allow a male dog to mount her. If successful copulation occurs during this window, fertilization is likely.
After estrus, the female enters the diestrus phase, which persists for about 60-90 days if she does not become pregnant. During diestrus, progesterone levels rise, further supporting the uterine lining and preparing it for potential pregnancy. If pregnancy occurs, the uterine lining thickens and remains intact to support the developing embryos.
If no pregnancy results from the estrus cycle, the female enters anestrus, a period of hormonal quiescence that can last 4-5 months before the next heat cycle begins. Throughout this process, it is essential for owners to monitor their dogs' behavior and health, ensuring they receive proper care and attention during each stage of the estrous cycle.