Animal models used in research are extremely important especially in the pharamaceutical industry and in universities conducting research. Toxicology tests are used on products like pesticides, medications, food additives, air fresheners, cosmetics, etc. Many vertebrates are used worldwide as test subjects. Mice, rats, fish, frogs and others are used. Animal rights activists will argue that there is no need to use animals for research and that computer simulations can model interactions between the environment, organs, tissues, organisms, etc. However, animals continue to be used for research. Louis Pasteur in the 1880's used sheep to demonstrate the transmission of anthrax. Pavlov's famous dogs in the 1890's helped demonstrate conditioned behavior. Dolly the sheep, the first mammal cloned from an adult sheep's cell was born in 1996. Dissection is still a useful hands-on activity in high school and college laboratories to teach comparative anatomy of various organisms from worms to pigs. When a new drug is tested, it usually is first tested on mice, rabbits or rats. Although these species are not humans, useful information can be gleaned from this research and applied to how it will affect people. Armadillos can be used to study leprosy. These are a few examples of why animal research is necessary. Regulations are in place that apply to animals, but vary from specie to specie. Under the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals in the U.S., any procedure can be performed on an animal, if it's justified scientifically. Pain relief is given unless it interferes with experimentation and other models and methods must be considered first before using an animal subject. Guidelines vary in different countries across the globe as to how animals are used in experimentation. There will always be debates regarding the ethics of animals used in research. For now, it seems to be a necessary part of scientific research.