Animals Used in Research. Once the impact of space on the dog was studied, then humans went to space trips. Despite growing recognition of the inadequacies of animal models and growing acceptance of alternative methods, animals continue to be used in research, testing and teaching in the United States every year. Genetically modiÞed animals (mostly mice) now make up over half of the animals used in research. Even a dog named Laika was trained and sent to a space trip to see if the animal could survive there. The terms animal testing, animal experimentation, animal research, in vivo testing, and vivisection have similar denotations but different connotations.Literally, "vivisection" means "live sectioning" of an animal, and historically referred only to experiments that involved the dissection of live animals.
Although these animals still endure the stresses and deprivation of life in the sterile laboratory environment, their lives are not recorded in official statistics. Nevertheless, the use of the 3Rs is crucial to continuously reduce the number and suffering of animals in research. Animals are used in research or experimentation in place of human subjects for various reasons..

Therefore, we support a healthy and continued debate on the use of animals in research. research on these animals. Although their physiology doesn’t identically mimic the human body, they act as ‘models’ for studying human disease, and are used to develop new treatments for diseases. Definitions. Human beings use animals for a wide variety of purposes, including research. The approximately 260 million people in the United States keep about 110 million dogs and cats as pets. More than 5 billion animals are killed in the United States each year as a source of food. Furthermore, a good regulatory regime—as found in the UK—can help to reduce further the number of animals used. Therefore, after years of efforts by many stakeholders, the Guide for the Care and Use of Laboratory Animals (Guide) was published in 1963, and today is on its 7th edition. Larger animals, such as pigs, dogs and monkeys, account for less than 2% of the animals used in research. The need for animal care standards and regulations for animals used in research was recognized not only by activists, but also by scientists using animals in research.
So animals are used in research mostly as pre-trial before trying on humans. Why we use animals.

The use of animals in research is prevalent because they share at least 200 common illnesses and diseases with humans.

Research is also done using insects and tiny worms such as nematodes, but this work is not Animals are used to gain understanding of some cell structures and physiological and pathological processes. HSI believes that complete transparency about animal use is vital and that all animals bred, used or killed for the research industry should be included in official figures.