Pregnancy is the period between impregnation and birth and usually lasts for about two months, or 63 days. Due to changes in the behavior of the dog, pregnancy can sometimes be mistaken for a disease.
During the first month, a pregnancy can easily go unnoticed. Often the only indicator is a female dog’s increased need to sleep. Additionally, females can experience nausea, especially in the morning, due to changes in their hormonal balance. She may eat less or even lose her appetite completely. Also, many females secrete a clear discharge from the vagina after becoming pregnant. Approximately from the fifth week, the dog’s stomach appears swollen. This first sign is not very distinctive especially when females are pregnant with smaller litters or, of they have a large body weight to begin with. Their abdominal girth increases with the progression of the pregnancy. Also, the female becomes calmer and calmer. At the same time the teats harden and turn pink. As they prepare for milk production the mammary glands increase in size. If the dog is pregnant for the first time, this process may take until after the birth to complete. Whereas with females who have already given birth before, milk production can begin before they give birth. Shortly before birth, the female increasingly licks her genitals. Vaginal discharge may also occur. The animal starts breathing rapidly and occasionally trembles. In dogs, birth can be divided into three phases: 1.The cervix dilates and makes way for the birth canal. 2.Contractions begin. The uterine muscles contract and press the fetus out of the birth canal. During this process the amniotic sac ruptures. 3. The female extensively licks the puppies to stimulate their breathing and afterwards bites through the umbilical cord. For every puppy the mother excretes a placenta, which is generally eaten by the female. After birth the dog’s vagina often produces a greenish discharge for a few days, often containing traces of blood.
The estrus cycle of a female dog depends on the season, and in general dogs go into heat one or two times a year. During these phases the animal is restless, presses to go outdoors, and secretes a slimy, bloody discharge from their vagina. This bleeding marks the preparation phase. After this phase, actual ovulation occurs. For three to four days the female-dog can be impregnated. If mating takes place during this time span, successfully fertilized eggs are embedded in the endometrium and the pregnancy begins.
During the first month of pregnancy examination by palpitation or imaging techniques may not produce a definite result. After the fourth week fetuses can generally be visualized via an ultrasound. However, the size of the litter can only be estimated. A more accurate examination requires an X-ray image, which is generally not done since it harms the unborn fetuses. In contrast to humans or horses the detection of progesterone (a pregnancy hormone) is not significant. However, there are newer methods that allow a pregnancy test from the 30th day of pregnancy.
For more information on pregnancy and birth, read the article on pregnancy in the advice section.