Lymph is a fluid that circulates throughout the body in the lymphatic system. It forms when tissue fluids/blood plasma (mostly water, with proteins and other dissolved substances) drain into the lymphatic system. It contains a high number of lymphocytes (white cells that fight infection).
Puppies normally get their first shots around 8 weeks old, but they can be given earlier if needed (ie with stray, abandoned pups or those who were formula fed). Three sets of combination vaccinations (a shot that protects against more than one disease) given at 3 week intervals. 8 weeks - first round.
The first set of puppy vaccinations are usually given at around 7 - 8 weeks of age, and then again around 10 - 11 weeks, and between 13 - 14 weeks. For Rottweiler puppies, a fourth Parvo vaccination should be given somewhere between 16 and 20 weeks of age for maximum protection.