My opinion on animal testing has varied a lot since first becoming vegan. Although I still dislike animal testing, I think that for medical purposes some types of animal testing are necessary and prove to be effective.
Though I am 100% against any form of animal testing which serves no real advantage for humans or animals alike - e.g. animal testing of cosmetics, food ingredients etc.
The biological make-up of animals does differ quite greatly from humans, and therefore medicine etc. often proves successful when tested on animals, but ineffective when used on humans. I think this form of animal testing is unnecessary and throughout the history of medicine overall it has proven to be unsuccessful.
After the first stages of animal testing are complete, the final product then needs to be tested on animals to record any possible side-effects and what dosage can be safely administrated before it becomes lethal. This form of animal testing I believe is most useful, because honestly how many people would be happy to take a new medicine which has never previously been tested on a living animal? In theory it might work, but there is no guarantee that it won't kill you or result in negative side-effects.
People need to remember that people are animals too. Is it really any worse to test on a fellow human being than it is to another kind of animal? Animal testing on criminals may sound good in theory, but in my opinion there are a lot of potential problems with the idea:
- A completely innocent person may have been wrongly labelled a criminal
- Although a person committed a crime, maybe their motives behind doing so are justified
- Laws vary a lot from country to country, so what may be legal for you to do here may be put you in gaol somewhere else
- Though someone has committed a crime, their time in gaol may see them change their previous ways and outlook on life.
How many people here would deny having any medical treatment if they were to become ill? What about your pet? If it became ill would you not take it to the vet? You may easily be able to say no now, but I don't think you can really know the answer until you are confronted with that situation.
Just like any other animal, it is our nature to want to survive and preserve our life for as long as possible - even if it means favouring your life over anothers.
I do agree though if humans improved their diet and other aspects of their lifestyle then many of the diseases which are prominent in today's society would be less prevalent and there possibly would be no need for any further research.
If anyone actually reads this long post

I don't expect you to agree with me, everyone is entitled to their own opinion. I just wanted to put forth my reasoning for my opinion on this matter.