Fimbriae (common pili) and flagella on the surface of bacterial cells. Left: dividing Shigella enclosed in fimbriae. The structures are probably involved in the bacterium's ability to adhere to the intestinal surface. Right: dividing pair of Salmonella displaying both its peritrichous flagella and its fimbriae.
Relaxin's peak is reached during the 14 weeks of the first trimester and at delivery. It is known to mediate the hemodynamic changes that occur during pregnancy, such as increased cardiac output, increased renal blood flow, and increased arterial compliance.
After 30 days of gestation, you can have your veterinarian measure your dogâs hormone levels to see if she is producing the hormone relaxin. Relaxin is only released during pregnancy, making the test relatively accurate. X-rays are probably the most effective way to determine if a bitch is pregnant.