This is probably a big reason why you see tons of articles about the next big treatment for X or Y coming out, and then the treatment/device is never heard about again. Reproducibility is and always has been a huge issue in science, and animal testing is no different. Although many different models exist to try to homogenize the process, there are so many steps along the way that contaminants can enter the process(breeding conditions, feeding the animals, genetic mutations, where the animals are sourced from). All of these things can cause differences in results for the same study when the species of animals are the same, not even considering when you jump from one species to another. However, there is no real substitute yet to replace this method of animal testing, so for now this is probably our best course of action.

I think that utilizing different species is not necessarily a bad thing when it comes to preclinical studies. As many have pointed out already it is important to recognize that there will be differences in how different animal and species populations react to a medical device within a study. For instance, there will almost certainly be a difference in the effective dosage in a drug study when it is conducted on a rat vs when it is conducted on a larger animal model like a dog or pig. This is not inherently bad and is often good practice in pre clinical testing as we can work in different scales to see the effective dosage in those models and deduce what would be effective in humans. Even with single animal studies, there is obviously differences in animal anatomy and human physiology so really it is not all that different in terms of using several different species. As I said before, I think in testing in multiple species we can better identify the safety and efficacy of a medical device before transitioning to clinical trials. 

I would like to argue however that the time it will take and the cost of the preclinical research would likely not be improved and if anything it would probably be more costly and time consuming to work with multiple animal populations rather than one. As you said each animal population will require different conditions that will have to be researched further and therefore consume more time in a multi animal study rather than a singular one. In addition to this, the cost of procuring these animals will definitely be higher if multiple animals species are selected. The reproducibility of the studies would likely be impacted to some degree as they would likely not be as reproducible as single animal studies. Different conditions would need to be in place for the different animal populations which ultimately would hinder the ability of the animal study to be repeatedly conducted. With that said I do think that designing a study around several different animal populations would ultimately improve the quality of the study as there would be greater sample of data from several populations to see what the effect of the medical device is before clinical trials.

Using a variety of animals improves reproducibility by ensuring that results are not limited to a specific species' unique physiology. Different animals, such as rodents, pigs, or monkeys, may respond differently to the same intervention, helping researchers identify which effects are robust and which are species-specific. This approach reduces the likelihood of false positives that might occur if only one model was used. Additionally, the probability that the results will have an unproblematic translation onto humans will be significantly higher since using a variety of animals enhances the reliability and validity of preclinical research. 

I think animal diversity can influence reproducibility of pre clinical research because every animal has different anatomy. What works for one animal might not work for another because of their different anatomy. This goes the same for people; what works for someone might not work for someone else. I think that is why researchers use a wide variety of animals in their research to see the changes and differences between them. Also, I would like to propose a similar question. Would it be more efficient if researchers tested on biologically or anatomically similar animals rather than animals with completely different anatomies? I personally think it can go both ways and it all has to do with animal diversity once again. On one hand, I think it is more efficient because it would be easier to study the differences of biologically or anatomically similar animals because these changes can shift the direction of how to develop new solutions for existing problems. But on the other hand, I think animal diversity is also important to see how their biology affects research. The purpose of testing animal models is because they have similar biologically processes as humans like the nervous system. They are tested to see how they react to certain things to move on to clinical trials. So in short, I think animal diversity is important to see the differences between animals because what works for one animal might not work for another, so you have to test different factors for each animal.

Animal diversity in pre-clinical research for medical device development is critical to ensure safety and efficacy before human trials. Different animal models, such as rodents, rabbits, pigs, and non-human primates, are selected based on their anatomical and physiological similarities to humans for the specific device application. For example, pigs are often used for cardiovascular device testing due to their heart’s similarity to human anatomy. Rodents, like mice and rats, are commonly used for initial biocompatibility and cytotoxicity studies due to their cost-effectiveness and well-characterized biology. Regulatory standards, such as ISO 10993, guide the selection of appropriate species to evaluate device performance and biological responses. Using a range of species helps identify potential adverse effects, such as inflammation or thrombosis, across diverse biological systems. This diversity strengthens the reliability of pre-clinical data, supporting safer translation to clinical trials.

Animal variety can play a major role in the reproducibility of preclinical research, both positively and negatively. On one hand, relying on a single animal model (such as rodents) can make results difficult to translate to humans because of species specific differences in physiology. Introducing diversity, such as pigs for cardiovascular research or non-human primates for neurological studies, can help capture a broader biological picture and increase the likelihood that findings are relevant to humans. Conversely, too much variation in animal models can complicate reproducibility across labs. If one study uses mice and another uses pigs, even when studying the same device, comparing outcomes becomes challenging. That is why collaboration and standardization are important. In my view, animal variety should be used strategically- not just to check boxes, but to ensure the results are biologically meaningful. Ultimately, integrating diversity with consistency in protocols could improve both reproducibility and the translational value of preclinical studies.

From what I have learned and from the experiences I have heard from other people, animal variety can have significant effects on reproducibility, on both sides of the spectrum. For example, having different types of animals in a study for different conditions could help to increase the scope of the study and could also help to better determine the effects that the device could have on humans. Although, this is a what if, since all animals are different and something that causes reaction Z in 9 different animals could cause reaction Y in the 10th different animal. It is in a sense unpredictable, but you have to take your chances. However, having different conditions or too many conditional differences would make it difficult to reproduce the pre-clinical research. It may increase the quality in some cases but may actually make it so that it becomes challenging to compare results. When looking at 2 different animals, their bodily reactions are different, so it is not the best to compare for example cow and sheep studies. The reproducibility of the research should be so that the end results would allow for people who replicate the process to compare the same results with each other, meaning for example sheep to sheep so that it can be properly analyzed. However, adding conditional variations may not be a bad idea because they can allow for a better scope and also possibly open up the floor to new reactions that may occur in the human body based on reactions that were not initially found with 1 type of animal.

I think using a variety of animal models is worth the added effort because it makes research results more reliable and ultimately safer when moving to human trials. If scientists only test on one species, there is a higher chance that important side effects or differences in effectiveness will be missed. For example, a drug might work well in rodents but fail in larger animals with physiology closer to humans. By testing across different models, researchers can spot those differences earlier, which saves time and money in the long run by avoiding failed clinical trials. Even though it may seem more expensive and complicated at first, the cost of a failed human trial is much higher than running more animal studies. That is why I think variety in animal models should be a priority in preclinical research. Do you think the benefits of reducing failed human trials outweigh the extra cost of using more animal models?