After seven days of natural mating of hamsters, the pregnancy diagnosis and gestational age of hamsters were checked daily using a veterinary B-ultrasound device equipped with an 8.5-MHZ linear probe. Male hamsters mature at 6-8 weeks of age and begin to reproduce at 12 weeks of age. Female hamsters usually mature at 5-6 weeks of age and can reproduce at 6-7 weeks of age.

Portable hamster B-ultrasound machine

In ultrasound examination, gestational sac diameter is an early diagnostic indicator of pregnancy and can only be reliably measured on the 7th day of pregnancy (Figure 1). The average diameter of embryonic vesicles was 11.2 ± 0.0 millimeters on day 7 and 25.2 ± 2.6 millimeters on day 17. The head diameter can be measured from the 10th day of pregnancy. On the 7th day of pregnancy, the average head diameter was 4.15 ± 0.46 millimeters, and on the 17th day, the average head diameter was 10.21 ± 1.58 millimeters. On the 7th day of pregnancy, the crown hip length was 7 ± 0.0 millimeters, and on the 17th day of pregnancy, it was 24.55 ± 1.2 millimeters.

Ultrasonic testing of hamsters

Ultrasound images of golden hamsters on the 7th day (a), 10th day (b), 12th day (c), and 17th day (d) of pregnancy. Estimate the gestational age of golden warehouse mice using crown hip length (CRL), gestational sac diameter (GSD), and head diameter (HD).

In macroscopic measurements of the fetus, head diameter can be measured from the 7th day of pregnancy. The average head diameter on the 7th day of pregnancy was 2.1 ± 0.31 millimeters, and on the 17th day it was 9.3 ± 1.77 millimeters. On the 7th day of pregnancy, the crown hip length was 6.19 ± 0.48 millimeters, and on the 17th day of pregnancy, it was 23.95 ± 0.91 millimeters. The total number of fetuses extracted from the uterus is 58, and the total number of hamster fetuses detected by ultrasound examination is 28.

Early pregnancy of golden hamsters can be detected through transabdominal ultrasound examination starting from the 7th day of pregnancy. Abdominal palpation, as a pregnancy diagnosis method, can start from the middle and late stages of pregnancy. For example, in rabbits, the gestation period is 30 days, and pregnancy diagnosis can be made through abdominal palpation starting from the 12th day of pregnancy. Ultrasound pregnancy diagnosis in animals is much more accurate than abdominal palpation.

Tumors and infections may be mistaken for pregnancy during abdominal palpation. Nowadays, with the advancement of high-frequency ultrasound imaging, accurate images of internal organs such as the hearts and kidneys of rodents like mice and rats can be obtained. A linear probe with a frequency range of 7.5-12 MHz has been used for ultrasound examination of pregnancy in experimental animals. Linear probes were found to produce higher resolution images at higher frequencies compared to curved probes.

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