While animals are being tested; Scientists say the animals feel no pain during but their appearance says otherwise. "To say that animal experiments involve pain is an understatement." Animals shouldn't be treated as lifeless objects and have chemicals injected into them. If scientists aren't studying the chemicals on humans then they shouldn't be testing it on animals.
Animals aren't the same
After having the chemicals injected into them they also have side effects "Penicillin kills guinea pigs but is inactive in rabbits; aspirin kills cats and causes birth defects in rats, mice, guinea pigs, dogs, and monkeys; and morphine, a depressant in humans, stimulates goats, cats, and horses." Meaning that the animals can no longer live their life normally.