Dog Heat Cycle

Dog heat cycle is the basic reason for the existence of any animal or plant is to pass along the germ plasma of which it is the custodian for the next generation. Everything about a plant or dog that help sit to live in harmonious relationship with its environment is working toward that end. A creature is a bundle of natural adaptations designed to ensure its own perpetuation. One of the most interesting tricks or arrangements is the female mating cycle.

At maturity a female dog usually is said to come in heat or come in season. Most dog come in season in what are called mating cycles. The primary influence that causes different species to start their mating cycles is the length of the day. We do not understand how light accomplishes these changes, which vary from one species to another.Dogs have a mating cycle in summer and winter, and that is usually all. There are can ids that regularly come in heat only once a year. This is the case with wild, doglike dog - the wolf and fox, for example that have litters only in the early spring.

The follicular hormone carries it through, and when the follicles rupture and discharge their eggs, athlete hormone ends it. At the same time a rather complex series of changes is going on in the dog's body. The mating cycle of the dog is fairly typical. An understanding of this process will help you handle your pet intelligently and may save you embarrassment if you own causewayed bitch.

Outwardly, the first signs of the season are the slight swelling of the vulva and increased appetite. For perhaps five days this swelling continues until a few drops of blood drip from the vulva. Some bitches bleed scantily and clean themselves so that no blood is ever seen. Others bleed fairly copiously. The first, or bleeding, period lasts from four to fifteen days. By the end of this period the discharge is pale red, almost straw-colored.

Inside the body the ovaries, which appeared smooth at the start, are showing the protrusion of the follicles as they enlarge. The uterus is growing longer and larger in diameter.

The second stage is initiated by a willingness on the part of the bitch to copulate. There may be a long teasing and playing period with the male dog, but eventually she will accept him. This is considered the first day of the second, or acceptance, period.

The follicles continue to enlarge on the ovaries, and the uterus and blood vessels are greatly increased in size. By about the sixth day of the acceptance period the follicles of the average bitch have ruptured and liberated their eggs (ovulation). It is possible to find bitches that ovulate the first day of the acceptance period, and others will be found that ovulate toward the end. If copulation has occurred, the sperm from the male (thousands of them) will be waiting around the ovaries for the discharge of the eggs so that one may fertilize each egg. Then the fertilized eggs move down the fallopian tubes and eventually come to rest at fairly even spaces from each other.

As soon as ovulation has occurred, a blood plug forms in each follicle.This changes into the luteal body that secretes the hormone whose presence in the blood effectively stops the mating cycle and mating behavior. Luteal bodies remain throughout pregnancy. If they are dislodged, the bitch aborts. After birth, the luteal bodies last for several months and their presence prevents another mating cycle.

During the copulatory, or acceptance, period the bitch mates repeat-edly, if allowed, but toward the end she "goes out" rather suddenly. Asthe luteal hormone takes effect, her behavior changes. She may fight offwilling males, and then just when the owner is sure the period is over she may play with and be teased by a male until she accepts him. These late matings often result in large litters, certainly larger than those of very early matings.