How Long Does It Take for a Pregnant Dog to Give Birth to Puppies? A Detailed Explanation of the Gestation Period

There are many methods for diagnosing pregnancy in female dogs. The more commonly used ones at present include external observation, palpation examination, ultrasound detection, hematological examination, and urine examination.

External observation method

About 1 week after mating, the female dog's vulva begins to contract and become soft and shrunken, a small amount of dark brown fluid discharge can be seen, and appetite is poor. At 2-3 weeks of pregnancy, the mammary glands begin to gradually enlarge, appetite increases greatly, the coat becomes glossy, the temperament becomes gentle, movement slows down, and she becomes calm and careful. A small number of female dogs around 25 days of pregnancy will show a period of pregnancy reactions, sometimes vomiting, poor appetite, and some will develop picky eating. At around one month, abdominal enlargement, sagging mammary glands, and elastic nipples can be seen, the mammary tissue gradually swells, and milk can even be expressed, body weight increases rapidly, and urination frequency increases. After 50 days, "fetal movement" can be seen on the ventral sides, and fetal dog heart sounds can be heard through a stethoscope on the abdominal wall. The disadvantage of the external observation method is that inexperienced people cannot judge early whether a female dog is pregnant.

Palpation examination method

When a female dog is about 20 days pregnant, the uterus begins to become thicker, and the increased diameter of the uterus can be clearly perceived by palpating the abdominal wall, but this requires a person with considerable experience to make a relatively correct diagnosis. After 25 days of pregnancy, the fetuses can be palpated (for example, feeling elastic fleshy spheres about the size of an egg). When palpating, care should be taken to distinguish them from non-elastic fecal masses. When palpating, the hand should be used to slide back and forth on the outer abdominal wall above the last two pairs of nipples, and rough or excessive force must be avoided to prevent miscarriage.

Ultrasound detection method

Currently, the commonly used ones include Doppler devices, A-mode ultrasound devices, and B-mode ultrasound devices.

The Doppler device examination method can be used to detect the fetal dog's heartbeat at 19-25 days of pregnancy. As the fetal dog develops, its accuracy increases. The accuracy rate is 85% at 36-42 days of pregnancy, 100% from 43 days of pregnancy to the end of pregnancy, and 100% for non-pregnant cases. For female dogs that are too small in body size, the misdiagnosis rate is slightly higher due to the pulsation of the abdominal artery.

The A-mode ultrasound examination method can be used for pregnancy diagnosis after 18-20 days, and at 32-60 days of pregnancy its accuracy rate is 90%, while the accuracy rate for non-pregnant cases is 85%. When using this examination method, the signal from a urine-filled bladder should be distinguished.

The B-mode ultrasound examination method is more effective than the Doppler device and A-mode ultrasound examination method. Its advantages are that it can detect fetal dogs at 18-19 days, and can even identify the sex, number, and whether they are alive or dead.

X-ray examination method

At 30-35 days of pregnancy, the shape of the uterus can be seen; at 49 days, the fetal dog's skeletal changes can fully show contrast. In a small number of female dogs, X-ray examination at 40 days of pregnancy shows the fetal dog's vertebrae and ribs clearly. When using this method, 200-800 milliliters of carbon dioxide must be injected into the abdominal cavity according to the size of the female dog.

Blood examination method

During pregnancy, the blood components of the female dog change. Based on changes in these parameters, it can be determined whether the female dog is pregnant, and pregnancy can be distinguished from pseudopregnancy.

From 21 days of pregnancy, red blood cells begin to decrease. By the last week of pregnancy, 70% of female dogs can decrease to 5 million/mL, red blood cell volume decreases by 40%, and the hemoglobin ratio declines, with the greatest decline in young female dogs and those improperly fed; erythrocyte sedimentation rate increases, reaching its maximum at parturition. From 20 days of pregnancy, hematocrit continuously decreases, dropping to the lowest value of 30 before labor, while that of non-pregnant female dogs is 45. From 21 days of pregnancy, platelets increase, reaching 500,000/mL before labor; white blood cells rise, reaching a maximum around day 49, then decline, but exceeding 30,000/mL is abnormal. At 28-42 days of pregnancy, coagulation factor concentration increases, until it declines at parturition. During pregnancy, fibrin protein increases by 2-3 times. At 21 days of pregnancy, serum creatinine levels decrease by 25%-33%; for multiparous female dogs the average is 0.8 (0.6-0.9) mg/L, and for primiparous female dogs the average is 1.1 (0.9-1.2) mg/L; serum gamma globulin decreases by 40%-45%; for multiparous female dogs the average is 648 (440-1220) mg/L, and for primiparous female dogs the average is 1108 (840-1460) mg/L.

Urine examination method

From 5-7 days after a dog becomes pregnant, a hormone structurally similar to human chorionic gonadotropin appears in the urine, so a human "rapid pregnancy test liquid" can be used to test whether the dog's urine contains a substance similar to human chorionic gonadotropin. If the test is positive, the dog is pregnant; if negative, the dog is not pregnant. The accuracy rate of this method is quite high, and it can be detected about 6 days after mating.