This topic is very interested to discuss because many people have different opinions about it. Ther are arguments both for and against it.
On the one hand, animals feel pain when humans experiment with them. Humans doesn't worried about the feels of the animals and they only look for their benefit.
Experimenting with animals is immoral because some animal testing, such as research in to cosmetics, is unnecesary and the people aren't awareness about the bad condition of a few animals testing.
On the other hand, many experiments are necessary to save a lot of lives of human diseases and cure many sick. Scientists have to think that they are doing the best work because they find the way to save lives.
In my opinion I'm against that the animals be used in unnecessary research and I think it is immoral because animals are too cute to suffer.