Before writing my thoughts I want to aver here that " I love animals" !!! Do not take my stand on this topic in any other sense please!!!

To sacrifice lives of a few beings, to save millions- how this can be immoral?
Use of animals in scientific research or testing the authenticity of a medicine is not a new thing. It has been there ever since the research started. It is more of a necessity. Animals are considered to be ancestors of humans and has DNA resembling closest to human's DNA . Hence, any kind of research or medicine is first tested on animals so as to get inkling of how it is going to affect humans or other animals.

Let us ponder upon aforementioned thought and relate it to history and our present. We have seen in history as well as in present scenario that there have been some great and brave people who have sacrificed their lives only to save million other people. Do you really call this immoral? Analogous to it scientists don't have any other option but to sacrifice some beings( more of animals) lives only to cure hundreds of diseases , to do research so as save humanity and to do several other noble work which can save lives of billion of people.Immoral is something when life of a being is not sacrificed but use for pleasure purposes like wearing its skin, eating its flesh or simple killing it as it gives amusement to some inane people. If something is immoral . it is the act of poaching or mass killing of innocent animals in the name of religion. When we hear cruel incidents like mass killing of dolphins in Denmark as a festival , mass killing of seals in Japan as a part of entertainment and many more such barbarous events , it goes way beyond the question of immorality. But, when their life is sacrificed to cure deadly diseases like cancer, AIDS , hepatitis , to save millions of innocent people it is acceptable or more so understandable. No matter how genius is the scientist who has developed a medicine , the medicine cannot be given directly to humans or patients. One single mistake can cause millions to loose their lives hence, animal testing is a way to prevent that mistake.

If there is something that we should stop , which is actually reprobate and cruel , then we should stop poaching, mass killing of animals, animals shows which involve torturous training and hunting for amusement .
The same work can be termed as moral or immoral , only the intentions behind that work make it different. Hence, the killing of an animal or being can be termed as immoral if the purpose is mere pleasure or can be termed as moral if the purpose is to save million other animals and humans.