What Happens to Animals During Animal Testing?

Experimenters use animals to test drugs, household products, cosmetics and chemicals to assess their safety for use with humans. A variety of tests exist that are sometimes very painful and distressing for animals, many of them resulting in death. Due to the difference in the biological make-up of animals, results from animal testing are not always relevant to humans.

Draize Eye Test

• In 1944, Dr. John H. Draize created the Draize eye test in order to evaluate eye irritation of various substances. In this test, an experimenter introduces a chemical into one eye of a restrained rabbit, leaving the other eye as a control. After one hour, he assesses the effects on the eye, and he repeats this every 24 hours for up to three weeks. Rabbits experience bleeding, redness of the eye, ulcers and blindness. Usually the experimenter will kill the rabbits at the end of the experiment.

Acute Toxicity Tests

• Acute toxicity tests ascertain the danger to various chemicals introduced via the mouth or skin, or through inhalation, usually with rats or mice. The original test is the Lethal Dose 50, which continues until at least half of the exposed animals die. Similar is the fixed dose method, where symptoms of ailment and suffering end the experiment, rather than death. The acute toxic class method and up-and-down procedure use fewer animals, but they suffer excruciating pain, convulsions, loss of motor function and uncontrollable seizures. At the end of the test, the experimenter kills the animals, carrying out a necropsy to assess internal damage.

Skin Irritation Tests

• The skin irritation test, or Draize skin test, monitors the severity of itching, swelling and inflammation on the skin of rabbits. It involves introducing a substance on a shaved area of skin, keeping another patch of shaved skin as a control. Often, these test results don't apply to humans, due to their differences in skin anatomy and structure.

Pharmacokinetic Tests

• Pharmacokinetic tests assess the rates of toxic chemicals in absorption, distribution, metabolism and excretion, usually using rats or mice. The animals take single or multiple doses of a toxic substance through force feeding, inhalation or injection. The experimenter examines blood samples while the animal is undergoing the test, and then studies the accumulation of chemicals on the organs of the dead animal. Differences in liver enzymes between species mean the results of the tests are not completely relevant to humans.

Pyrogenicity Testing

• A pyrogen is a chemical that creates a rise in body temperature. Pyrogenicity tests studies fever side effects in vaccines and injectable drugs. Since the 1940s, experimenters have used the rabbit pyrogen test to assess temperature increases, after injecting a substance into the bloodstream. The different age and gender of rabbits highly affects the results so can sometimes misrepresent data. More commonly used now is the Limulus amoebocyte lysate test, where blood from horseshoe crabs tests the effect of pyrogens on the immune system.