Sheikh Sa`d al-Shuwayrikh
If these laboratory experiments are being conducted for some real benefit that cannot be achieved without them, then carrying out such experiments is permissible. The reason for this is that all animals have been made subject to human welfare.
However, it would be impermissible to do such experiment just for fun and for groundless reasons, since this would be plain torture and it is prohibited in Islam to torture animals.
Also, even if the experment itself is valid, every care should be taken to make the subject animal as comfortable as possible. No animal should be subjected to any unnecessary discomfort.
Source: Islam Today