animals serve as guinea pigs for testing drugs, vaccines, cosmetics and even cleaning products that can be done in different ways. Guinea pigs, mice, rabbits and monkeys are the animals most used by scientists, but in some cases, dogs, pigs and even cockroaches are also used. The animals that participate in the experiences are raised in nurseries called vivariums and usually are sacrificed after the study. Animal rights advocates repudiate these tests, claiming they are cruel and useless, but scientists argue that without them, medical advances would be heavily impaired.
RED-EYED
Guinea pig rabbits measure the chemical effects of applying cosmetics
1 The product is dropped into the animal’s eyes. Rabbits are easier to handle and have large eyes, which allows the visualization of reactions caused by the substance.
2 As the products can cause pain, irritation and burning, the rabbits are immobilized and wear braces around their necks. This prevents them from mutilating themselves by gouging out their own eyes.
3 It is also common to use metal clips on the eyelids to keep the guinea pig’s eyes open at all times, which helps in observing the effects of the drug being evaluated.
4 The study is usually performed without anesthesia and, as a reaction to the tested substance, inflammation, ocular ulcers and hemorrhage may occur. In extreme cases, the animal can go blind.
5 At the end, the rabbit is sacrificed to analyze the effects of the substances on its organism. Critics of the test say it’s useless because rabbits’ eyes have a very different anatomy than ours.
DOPED RODENTS
New drugs are developed based on animal testing
1 The new medicine is tested in the laboratory. In the case of a cancer drug, for example, the researcher tests its effectiveness on a culture of cancer cells in a vial.
2 When the results are promising, the second phase is carried out: the study in animals. Mice, because they have a short life cycle and easy reproduction, are used in experiments
3 First of all, it is necessary to “infect” the rodent with the disease. In the case of a new cancer drug, this means growing a tumor, similar to growing cells studied in the laboratory.
4 The new drug is applied to prove its efficacy and toxicity. A study analyzes how it is processed by the body – sacrificing the animal – and whether it has effects on reproduction
5 Depending on the results, drug development is ruled out. If the test is successful, the product proceeds to the last stage, when it will be tested by patients
LETHAL DOSE
Substances are injected into the animal to determine how toxic they are to humans.
1 A gastric tube is inserted into the animal’s throat to force it to ingest the substance to be tested. Monkeys, because they have an organism similar to ours, are the most used guinea pigs in the study.
2 The tested substance almost always causes pain, convulsions, diarrhea, bleeding and internal injuries in the animals. It can also be inhaled or administered through injections.
3 The objective is to know what is the maximum dose that the body can withstand. Therefore, even if the substance is safe, it is common to seek a concentration that leads to the death of guinea pigs.
4 The study is carried out in a group of animals and lasts a few days until half of them die – hence the name LD 50 (acronym in English for lethal dose 50%). Those who survive are also sacrificed
– The substances tested are usually in products for daily consumption
PROS AND CONS OF ANIMAL TESTING
For the sake of science or the rights of lab animals
SCIENTISTS
Without tests, pharmacy shelves would be empty. There would be no way to create new medicines without trying them first on laboratory animals. The scientists also point out that they follow strict protocols and codes of ethics that guarantee the well-being and prevent the suffering of the animals.
DEFENDERS
This year, the European Union approved new rules that restrict the use of animals in scientific tests. The measure is the result of protests by organizations that are against such experiments. Activists say the studies are ineffective and that dangerous drugs, such as thalidomide, ended up on the market even after being tested.
STRONG SOOTHING
Thalidomide was introduced in the 1950s as a sedative. But, when ingested by pregnant women, the drug caused malformation and absence of limbs in the fetus.
SOURCE People for the Ethical Treatment of Animals (Peta), biologist Paula Jimenez, Brazilian Association of Thalidomide Syndrome Carriers (ABPST)