Animal experiments are most commonly conducted with guinea pigs, dogs, and nonhuman primates. Usually, these animals are used to test the safety and effectiveness of pharmaceuticals, cosmetics, household cleaners, food additives, and pharmaceuticals, and test the efficacy of novel medicinal products. There is a risk of causing physical and psychological suffering to the animals. There is often great suffering associated with the procedures. Almost all animal experiments end with the death of the animals, but some are reused in subsequent experiments. It is common practice to deprive animals of food and water, inflict wounds, burns, and other injuries, and expose them to drugs, chemicals, or infectious diseases. Experimental and test procedures are cruel and unnecessary since animals are unwillingly subjected to pain and suffering.

Rats and mice are the most commonly used organisms for animal testing in research. What I didn't know about before was that they are not protected under the Animal Welfare Act, which sets minimal standards for the care, housing, sale, and transport of animals used in research. Due to them not being protected under the Act, data on how many mice and rats are used each year for research in the U.S., for what purposes, and the pain and/or distress experienced by these animals, is not gathered or reported by the USDA; there is only a rough estimate of 93% of animals used in research facilities being rats. Bird and cold-blooded animals are also not protected under the Animal Welfare Act. Other commonly used animals that are protected under the Animal Welfare Act include guinea pigs (22%) and rabbits (17%).

As someone who does research in academia, I do think that animal testing is necessary in order for us to make advancements in science. I do find it a bit naïve for people to claim that animal testing should be completely cut out because then how will further medical devices or medicines be produced in the future. Human trials cannot be done once a new experimental drug is created as there is not evidence or risks established. In no way am I saying that all animal testing is ethical or alright. In fact I think that the majority of cosmetic testing on animals is cruel and could be severely limited or avoided completely. However, unfortunately in order for some research to progress and to improve our understanding of drug delivery systems, diseases, and other general ailments, animal testing is necessary. 

Information obtained here: https://aavs.org/animals-science/animals-used/mice-rats/

Another group of animals that is becoming an increasingly more popular alternative to hamsters, mice, and rats in scientific research are fish. This alternative is mainly due to the fact that fish are cheaper as they are considered a 'phylogenetically lower species'. Similar to the prior post, fish are not protected under the Animal Welfare Act. The zebrafish has become a popular fish in respect to research in studying vertebrate development and physiology. This is because the zebrafish embryos are transparent, develop outside of the mother, and hatch within three days, avoiding the pitfall of lack of supplies that other animal groups face. In addition, zebrafish and humans share many similarities in genetic making them ideal for genetic disease research. Their short lifetime also allows scientists to view lifetime diseases that are unreasonable to observe in a human. Overall the zebrafish has provided strong advantages that have been very beneficial in pre-clinical studies for biomedical research. 

Fish are becoming more popular alternatives to mammals in biomedical research mostly because we, as humans, do not fully understand how they feel pain. Do you think a fish is more expendable than a mouse or any other mammal in that manner?

A less explored species in animal research is the common fruit fly. They offer remarkable advantages such as tiny size, low cost to maintain, can be kept in vast numbers, easy diet, and low breeding time. Drosophila and human genes have 60% similarity, depict few characteristics of human behavior, and share the same biochemical pathways. On the other hand, rats, dogs, and fish are expensive and demand more maintenance. Another advantage of flies is their more superficial anatomy and small size, allowing them to observe processes under a microscope easily. Although I haven't seen it much in labs or used in research. Would like to know if anyone has experience with fruit flies.  

The testing of animals is crucial in scientific research to obtain understanding and analyze the safety and effects of outside variables on biological systems.  Other animals that are commonly used for animal testing in research include nonhuman primates, rabbits, and farm animals.

Nonhuman primates, most commonly macaques, are often used as models due to their behavior and cognitive abilities like that of humans. Nonhuman primates have been utilized in experiments related to infectious diseases such as AIDS, malaria, Lyme disease and Ebola and are used in toxicology and vaccination studies. Rabbits are used in experimentation for more practical reasons as they are small, cheap, submissive, and have short gestational periods. Farm animals are also used as models of human conditions. During the experiments, the models suffer great physical and psychological distress.

To answer @kaf43 ‘s question, I do believe that fish will be considered more expendable. As humans do not fully understand the sensation of pain in fish, scientists may abuse their usage of fish and not value their lives as they would other animals.

I do think it's interesting to discuss using other, less conventional animal species in pre-clinical trials, especially because it could help with supply issues. In the post-pandemic world we're living in, I wouldn't be surprised if lead times for laboratory animals are even longer with all the supply chain challenges going on. However, although some species may be more easily attainable, it is important to consider whether the biological system being examined in the chosen animal closely resembles that in human beings, otherwise the results of the study won't mean anything. The reason why rats and rabbits are so commonly used for in-vivo studies is in part because they are mammals, and thus their general physiology is very similar to that of humans. The further away genetically you get from human beings, the more variables you introduce that may impact your results.

With the exception of rats and mice, swine or pigs are also a rather commonly used animal for testing purposes. Because they are biologically and physiologically similar to humans, including their cardiovascular, pulmonary, skeletal, and integumentary systems, they are specifically fitted for biomedical testing even more so than mice and rodents. Swine biology has been used as a model for various topics of biomedical research including but not limited to diabetes, alcoholism, peptic ulcers, liver transplantation, etc. They are also the primary species of interest for tests involving xenograft transplant tissues. I would say the benefits are palpable already and there are still many research topics surrounding porcine testing that may lead to even greater gains for the biomedical community, as demonstrated by Duke University's research on porcine islet cell injection into a baboon which, according to Duke researchers, may eliminate the need for insulin in Diabetic patients. Funny enough, the miniature pig is genetically bred for research purposes, and are slowly yet surely gaining popularity on par with rodents for biochemical or genetic testing purposes. On the topic of ethics, because pigs are considered farm animals, while the Animal Welfare Act cannot protect them due to pigs being mainly farm animals, there are regulations put in place to ensure and determine that they are not in any distress or pain, at least int eh farm animal setting. For biomedical purposes, depending o what type of a response researchers wish to provoke for the animal, perhaps it requires the animal to be in in distress, pain, etc. However, it is somewhat optimistic to know that there are rules and indications for when an animal is in pain/ distress and directions on how to handle such a situation.

After going through this thread I see that animals such as mice, rats, and primates have already been mentioned so I wanted to investigate other species. One animal model that the research lab that I work in uses chinchillas. In my research lab our primary purpose for the use of chinchillas was to investigate the auditory effects post blast induced traumatic brain injury. We specifically analyze the auditory cortex and inferior colliculus as these sections in the brain are highly researched when investigating auditory damage. Other uses of chinchilla in a research setting include upper respiratory tract infections, and other facets of auditory damage such as psychoacoustics and ototoxicity. After doing a brief literature search it was apparent that chinchillas are a preferred animal species when it comes to auditory research. In terms of human testing, the research that my lab conducts could further translate to human research down the line when - for example, when a soldier returns from warzone conflicts they might have experienced blast induced traumatic brain injuries and the auditory cortex and inferior colliculus can be examined similar to how the chinchillas were tested.

@sandra-raju 

I think it is a very difficult discussion, but indeed necessary. We have made extraordinary strides in science and medicine due to animal testing being implemented in research and development. I will not negate the traumatic impact on any animals bred for research, but there is a significant purpose and one that we as humans have all benefited from. Animals species used for research is crucial to our survival and currently we still do not have enough technology to make these advancements without their help. Do you foresee future innovations that could allow us to not rely on animal testing? Do you think AI can be an alternative?

Using animals for research is very important to studying the needs for the humanity. Some will agree some will disagree. Some may see that using animals for research is cruel. The most common animals used in research are rodents. The rodents like mice, rats, guinea pigs, and hamsters are most commonly used in research. My question is why did the use of chimpanzees decrease over the years if their genetic makeup is closest to the genetic makeup of humans? Wouldn't it be more reliable to use an animal that is similar to humans? I feel like the process to discovering the needs for humans would be a lot faster and more sufficient. I understand that the number of rodents exceeds the number of chimpanzees, but does quality over quantity not fit in this situation? When emergencies arise such as COVID, do they consider animals with the closest genetic information to be on the front lines?

@danieshat1 As a science minded person, I agree that testing should be conducted on species with similar genetic makeup as humans. However, as an animal lover, I think regulations regarding testing on animals should be in place. If chimpanzees are genetically related to humans, wouldn't that mean that they can experience similar pain and symptoms? To answer your question, the use of chimpanzees decreased, especially within the past 10 years, because the National Academy of Medicine and National Institute of Health confirmed that experiments on the animals were unnecessary. Studies showed that post-experimented chimpanzees exhibited abnormal behavior. They displayed depression and post-traumatic stress. Symptoms included social withdrawl, anxiety, and loss of appetite. With the progression of science and technology, I am hopeful that pre-clinical testing and observation can be conducted on animals and humans without unethical methods that inflicit pain and suffering.