The main reason why animals should not be tested on is because of the suffering they have to go through every day in those labs. For instance, according to Down to Earth Organic & Natural, when being tested for cosmetic or pharmaceutical products, "Animals endure chemicals being dripped into their eyes, injected into their bodies, forced up their nostrils or forced down their throats. They are addicted to drugs, forced to inhale/ingest toxic substances, subjected to maternal deprivation, deafened, blinded, burned, stapled, and infected with disease viruses." This cruelty is also sometimes pointless due to the differences between animals and humans and how different diseases affect them. For example, "More than 95% of new drugs that test safely and effectively in animals go on to fail in human clinical trials. For some diseases, the failure rate is even worse—studies of cancer drugs have a 96.6% failure rate, and studies of Alzheimer’s disease have a 99.6% failure rate." (PETA, 2021). Giving more reason as to why animal testing should stop. Instead of animal testing, we can use dermatological testing. If we did this, then the countless lives of the animals that are tested on in cosmetic or pharmaceutical labs would be saved and their suffering would end. 

How would you feel if people took you into a laboratory to test a new product? They have no idea what will happen or what you will experience, so they are using you to find out. You would not want to be there, right? Almost all of the animals that go through this experience DO NOT come out alive. So, if you were in the situation, you would most likely not come out alive either. Don't you want to live? You deserve to have and live a good life. So do these animals. Help save these animals lives and end their suffering.