Answers: 1.Circulatory system-pumping blood to and from the body and lungs with the heart 2.Digestive system-digestion and processing food with salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, rectum, and anus.
During the tie, the male turns around so the dogs are back to back and can defend themselves. The tie typically lasts 20 to 40 minutes. It may be just a few minutes, and dogs can mate successfully without becoming tied at all. The evolutionary reason for the tie is unknown, but it's assumed that if a male dog is tied to a female, it prevents other males mating with her. Unwanted Mating.
Tying the Knot. 1  1. Make a U-shape.Pull a long cord into a U or horseshoe shape. so that the ends are close together. 2  2. Pull the cord into a loose loop. Pull one end past the other so that they overlap by about four inches (10 cm). 3  3. Double back the outer cord end. Bend the tip and bring it back along the outside of the loop.