How does the lock proceed in dogs? - briefly
The locking mechanism in dogs is primarily governed by the estrous cycle, with the female dog typically entering heat (estrus) approximately every six months. During this period, which lasts about 3 weeks, she becomes receptive to mating and can be bred.
How does the lock proceed in dogs? - in detail
In dogs, the process of going into heat, also known as estrus, is regulated by a complex interplay of hormones and physiological changes. The entire cycle, from proestrus (the beginning of heat) to diestrus (the end of heat), typically lasts around three weeks.
During the initial phase, known as anestrus, there are no visible signs of heat. This is a period of hormonal quiescence where reproductive hormones are at their lowest levels. The follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland are minimally active, as are estrogen and progesterone from the ovaries.
The cycle begins with proestrus, which marks the onset of heat. This phase is characterized by a surge in FSH and LH levels, stimulating the growth of follicles within the ovaries. As these follicles develop, they produce increasing amounts of estrogen, leading to noticeable physical changes in the dog. The most prominent sign is the swelling of the vulva, which may also become red or pink. Other symptoms include increased urination to mark territory and attract males, as well as a bloody discharge from the vagina.
The next phase, estrus, is when the female dog is most fertile and receptive to mating. During this time, LH levels peak, triggering ovulation—the release of mature ova (eggs) from the follicles. This phase is shorter than proestrus, typically lasting about 9 days, but it can vary significantly between individual dogs.
Following estrus, the dog enters diestrus, a period marked by high levels of progesterone produced by the corpus luteum, which develops from the remnants of the follicles after ovulation. Progesterone maintains the uterine lining (endometrium) in preparation for potential pregnancy. If fertilization occurs, the corpus luteum continues to produce progesterone, supporting the pregnancy. If no fertilization takes place, the corpus luteum degenerates, and both estrogen and progesterone levels drop, signaling the end of diestrus and the beginning of a new cycle.
Throughout these phases, careful observation and understanding of the dog's behavior and physical changes are crucial for determining the optimal time for breeding or instituting preventive measures to avoid unwanted pregnancies.