How Many Animals Are Used In Research? A Deep Look At The United States & Canada
By some estimates, 190 million animals are used in research globally each year. Despite this figure being miniscule compared to the 85+ billion animals killed for food annually, animals used for experimentation and research often live horrible lives and are subjected to extreme acts of violence. Indeed, the Canadian Council on Animal Care (CCAC) has five categories to classify the level of invasiveness of scientific procedures on animals, ranging from research on invertebrates and live tissues (which is itself problematic as invertebrates can likely feel pain), to little or no stress, and finally, severe pain. The United States Department of Agriculture (USDA) has similar pain categories (see Table 1 below).
In 2024, close to 3% of animals used in science at CCAC-certified institutions (just a little over 98,000 animals) were subjected to the highest category of invasiveness (see Table 2). In the U.S., this figure was 7% (around 55,500 animals; see Table 3). The percentages rise to 24% in the U.S. and to 30% in Canada when considering the second-highest category in the same year (category D). However, these categories only consider protocols performed on an animal, which means they ignore the negative welfare impact of standard laboratory housing, which increases overall mortality and severity of disease in captive animals.
Indeed, the quality of animals’ lives versus the number of animals used in research was the main question that my PhD dissertation sought to answer: is it ethically more acceptable to use a greater number of animals with each experiencing fewer procedures, or to use fewer animals with each experiencing more procedures? As with many dissertations, I didn’t come to a neat conclusion with my own data.
However, this debate is limited by black-and-white thinking as it doesn’t allow for alternative answers like the complete replacement of animals used in research or at minimum, establishing universal ethical guidelines for non-human animals. For instance, the latter would only encourage animal research that would have direct benefits for the individual animals involved, or studies in which the animal doesn’t show signs of dissent.
There are annual reports by government agencies that show the number of animals used in science by species, and some academic research that shows the overall number of animals used over time, but there isn’t a concrete, accessible resource that illustrates animal use by species and year. Because Canada and the U.S. are among the top ten animal-using countries for science and research, and because both countries have data available for their animal use numbers (since 1973 for the U.S. and since 1985 for Canada), we set out to explore annual trends among both countries for a variety of species, such as cats, dogs, monkeys, guinea pigs, rabbits, and more.
The purpose of this blog is to help advocates in these regions understand which species are most commonly used in science and why certain spikes and decreases happen over time. In it, we’ll also analyze the percentage of animals exposed to different levels of invasiveness/pain in recent years (2021 to 2024) to better understand what happens to animals used in science in Canada and the U.S. (see Tables 2 and 3 above).
We also examine the CCAC’s “purpose of animal use” data (e.g., fundamental/basic science, medical purposes, regulatory testing, product development, and educational purposes; see Table 4) to better understand some trends, although this type of information isn’t available in the USDA datasets. The most recent “purpose of animal use” datasets are available through the CCAC’s website (they are named ‘Sortable Excel File 2’ under each year).
Data Caveats
CCAC
The CCAC, a non-profit organization, only reports data from CCAC-certified institutions, which are typically universities. Thus, CCAC data excludes most private laboratories and companies unless they receive government funding for their research. Additionally, there might be inconsistencies between institutions as the CCAC doesn’t provide standardized methods or guidelines for institutions when they submit their animal use numbers. The CCAC also implemented changes to their data collection procedures — once in 1996 and again in 2011 — which may present some inconsistencies in data reporting as well.
Further, while the CCAC presents data on the type of research being done, there are only five broad categories (fundamental, medical, regulatory testing, development of products, and education), which makes it difficult to track specific studies to explain animal usage.
Lastly, the CCAC doesn’t differentiate between wild animals brought into a laboratory versus wild animals studied in the wild, so it’s hard to identify which percentage of all animals reported to the CCAC are studied outside of a lab.
USDA
The USDA, a government agency, reports data from USDA-registered research facilities, federal research facilities, and Veterans Affairs research facilities, as required by the Animal Welfare Act (AWA). Similar to the CCAC, the USDA data includes research conducted on wild animals, but doesn’t differentiate between wild animals brought into a laboratory versus wild animals studied in the wild.
The biggest limitation with the USDA data is that it excludes laboratory-bred mice, rats, birds, reptiles, amphibians, crustaceans, and fishes because the AWA doesn’t protect them, and these animals make up 95% of animals used in research in the United States. As of 2024, birds not bred for research are now required to be reported (i.e., the new category, “Birds,” could include birds captured from the wild and used in research, but not those bred in captivity for research purposes).
The USDA summary reports also omit farmed animals and non-protected species (e.g., fishes, reptiles, laboratory-bred mice and rats, etc.) reported by Agricultural Research Services facilities from the final numbers. In 2024, the USDA updated its data collection form with new categories, including “Other Farm Animals,” “Other Mammals,” and “Birds,” so long as these animals were not used for agriculture research or bred specifically for research purposes. In other words, animals used in agricultural studies or bred in captivity specifically for research are not counted. As such, the U.S. charts below present an incomplete picture of farmed animals used for research purposes, in addition to excluding non-protected species.
Despite these limitations, both agencies provide informative trends on animals used in science over time, even if liable to noise and errors.
Canada
Overall Use
Based on data from the CCAC, the graph below shows animal use in science over time in Canada, with different lines representing different animal categories, including total use.
The total number of animals used in science in Canada has been steadily increasing, peaking in 2020 and dropping since, although the number recorded in 2024 is almost two times higher than it was in 1985 (approximately 3.7 million versus 2 million animals). Despite the limitations of the CCAC data, the fact that the number of animals used in science is increasing is alarming, especially considering the technological advances over the last few decades that have been developed to replace animal testing with alternatives.
Birds
Birds are commonly used for biomedical research (e.g., to study human diseases) and agriculture research (e.g., to improve productivity and welfare of farmed chickens). In Canada, the total number of birds jumped 2.5 times from 2018 to 2019 (from approximately half a million to over a million) and increased two times again from 2019 to 2020 (from approximately 1 million to 2.5 million). Most of the birds reported to the CCAC in 2019 and 2020 were chickens used in category B research, or “little or no discomfort.”
In 2019, 70% of all chickens (over 780,000) were used in one medical study belonging to the lowest invasiveness category, while in 2020, 91% of chickens (almost 2.3 million) were used in one product development study belonging to the lowest invasiveness category. These large numbers likely reflect agriculture research (i.e., research done in collaboration with the egg or meat industry) as chicken barns in Canada can hold up to 50,000 birds. While the peaks in 2019 and 2020 reflect chickens used in protocols classified as causing “little or no discomfort or stress,” these classifications overlook the poor welfare conditions inherent in industrial farming for both egg-laying hens and chickens bred for meat.
The number of birds dropped to under half a million in 2021 and continues to decrease, with most of these (74–80%) being used in category B research (“little or no discomfort”) from 2021 to 2022, while more birds were used in category C research (“minor pain”) in 2023 and 2024 (44–60% of all birds).
Mice
The number of mice decreased after the mid-1980s, but has increased since the late 1990s and currently remains at a steady plateau. Indeed, mice are one of the most commonly used species within Canada — and globally.
The spike in the use of mice since the 1990s is due to genetic engineering, which allowed scientists to create many new strains of mice and use them as biomedical models to study how specific genes affect health, development, and disease. As a result, scientists began to view laboratory mice as “mini humans;” with little ethical oversight, researchers can subject them to different diseases and illnesses that would be unthinkable to do with humans, even though translatability rates are low (e.g., we’ve cured cancer in mice, but not in humans).
From 2021 to 2024, around 1% of all mice were used in research causing severe pain. While that sounds low, 1% still represents tens of thousands of individuals being subjected to extreme pain. Perhaps more distressing is that 62–69% of all mice were exposed to protocols causing moderate to severe distress (category D). Even worse, 57–64% of mice used in category D research were used for fundamental research from 2021 to 2024: In other words, between 400,000 and 600,000 mice were purposely stressed for basic science.
Fishes
Fishes are one of the most used species in science in Canada and globally. Despite the fluctuations in the graph, there has been an overall increase, with the first highest peak observed in 2009 (just a little over 1.6 million), and the number then waffling over and under a million fishes since. For example, in 2020, close to 600,000 fishes were reported to the CCAC, but this number rose to over a million in 2021 and then increased to its highest peak in 2024: 1.7 million fishes.
The rising popularity of fishes in science can be attributed to their use as a biomedical model (replacing rodents as a go-to), the fish farming industry (e.g., fish welfare research), and climate change (e.g., ecological research using fishes to study the impact of global warming).
Zebrafishes, salmon, and trout were some of the most commonly used fish species between 2021 and 2024, together making up 64–84% of total fishes used. Overall, fishes were more likely to be subjected to more painful procedures compared to other species: 6–7% of all fishes were used in research causing severe pain from 2021 to 2023, although this dropped to 4% in 2024. Like mice, many of these painful protocols were used in research for basic science. For example, from 2021 to 2024, 63–85% of zebrafishes exposed to protocols of moderate to severe distress were used for fundamental research.
Rats
The total use of rats in science in Canada has been low overall and steadily declining over the past few decades, and worldwide, mice have replaced rats as a genetic model for human conditions. Mice are also perceived as more cost-effective than rats given their smaller size, resulting in fewer rats being used overall.
Similar to mice, a low proportion of rats were exposed to protocols of the highest severity, ranging from 1–4% of all rats between 2021 and 2024. Approximately 50–52% of rats were subjected to protocols causing moderate to severe distress during the same time period. Similar to mice and fishes, many of these painful protocols were used for basic science: from 2021 to 2024, 33–44% of rats exposed to protocols of moderate to severe distress were used for fundamental research.
Guinea Pigs
Like rats, the use of guinea pigs in science has been low — dropping from approximately 45,000 in 1993 to just over 8,000 in 2024. Again, guinea pigs are seldom used because mice are a preferred model to study human conditions. For example, mice are more likely to be used to look for skin allergy reactions, when it used to be more common to use guinea pigs. Additionally, guinea pigs were commonly used for tuberculosis testing, but scientists have now moved towards in vitro methods (e.g., analyzing animal or human cells in a petri dish).
Unlike rats and mice, a higher proportion of guinea pigs were exposed to the most invasive protocols, ranging from 13–40% of all individuals from 2021 to 2023, with most of these being for regulatory testing of products (73–94% of guinea pigs exposed to category E). However, the percentage of guinea pigs used in the most invasive research dropped to 3% in 2024.
Rabbits
Rabbits are one of the least commonly used animals in Canada and their use in research has been steadily declining from around 36,000 in 1985 to just under 4,000 in 2024. Further, rabbits were rarely exposed to the highest level of invasiveness in Canada (e.g., 2 to 16 rabbits were subjected to protocols causing severe pain between 2021 and 2024). However, a larger proportion were still subjected to the second-highest level: 43–56% of all rabbits were involved in protocols causing moderate to severe distress (category D) during the same time period.
Some scientists speculate that the worldwide declining trend of rabbits is likely due to “the global protest against the use of animal[s] for experimentation, which diverted the biomedical research towards more in vitro studies.” Indeed, the infamous Draize test, which was developed to test the irritable effects of household and cosmetic products on the eyes, has a long history in anti-vivisection advocacy. In the test, rabbits are restrained to prevent movement or rubbing of their eyes while the product is applied directly onto their eyes.
Anti-vivisection campaigns in the 1980s and beyond were successful in getting companies to drop the Draize test and eventually in getting 45 countries to ban or limit animal testing for cosmetic products and ingredients. What’s more, the iconic bunny logo (shown below) is now a well-known symbol found on household and cosmetic products to verify that the product hasn’t been tested on animals (e.g., the Leaping Bunny Program in Canada and the United States). Unfortunately, some companies use fake bunny logos to appear cruelty-free, which is why it’s important for advocates to familiarize themselves with legitimate cruelty-free certifications.
Figure 8. Leaping Bunny Logo
Monkeys
While the overall use of monkeys is much lower compared to other species, there has been a slight upward trend in their use in Canada and worldwide since the onset of COVID-19; monkeys are one of the most popular animals used for drug and vaccine research.
Indeed, the number of monkeys used in Canada for science reached its highest peak in 2023: a record 12,138 were reported to the CCAC, which was approximately 1.5 times higher than the previous and following years (just under 8,000). Most of these monkeys were cynomolgus macaques (72–80% of all monkeys from 2021 to 2024), also known as long-tailed monkeys, which are commonly imported from Cambodia and are listed as endangered.
The 2023 peak is alleged by PETA to be the result of the giant pharmaceutical company, Charles River Laboratories, using Canada as a loophole for monkey shipments as the company temporarily halted monkey importation from Cambodia into the U.S. in 2023 after a five-year investigation found that imported monkeys were trafficked (i.e., plucked from the wild instead of being bred on a monkey farm). Specifically, PETA alleged that monkeys imported into Canada since 2023 were reclassified as “specimens,” allowing their blood and tissue samples to be sent to Charles River Laboratories in the U.S. — effectively circumventing U.S. import restrictions.
The level of invasiveness for procedures on monkeys varied from 2021 to 2024. In 2021, 39% of all monkeys were used in category D protocols (moderate to severe). This increased to 50% in 2022, then dropped to 26% in 2023, and again increased to 50% in 2024; 84–90% of these protocols being cataloged as regulatory tests and product development research. Like rabbits, monkeys were rarely exposed to the highest level of invasiveness between 2021 and 2024: ranging from none to 38 monkeys (all of them being cynomolgus macaques).
Dogs & Cats
The number of dogs and cats used in science in Canada has remained relatively low over the last 30 years compared to other animals, likely due to the controversy of running experiments on companion animals (i.e., people are generally less supportive of using companion animals for animal-based research).
In general, more dogs than cats are used in research. This is because dogs have more genetic variation (e.g., over 300 dog breeds compared to about 70 cat breeds) and dogs are a preferred model for studying cancers as they develop the same type of cancers as humans. In 2023, the number of dogs reported to the CCAC increased by 1.5 times from the previous year, jumping from around 10,000 in 2022 to approximately 16,000 in 2023, although this dropped to under 10,000 in 2024. In contrast, between 4,000 and 5,000 cats were reported to the CCAC during the same years.
Dogs and cats are categorized by the CCAC as purpose-bred (i.e., bred specifically for scientific procedures, like the beagle dog) or randomly sourced (e.g., shelter animals). From 2021 to 2024, 93–97% of all cats reported to the CCAC were randomly sourced. In contrast, 38–49% of all dogs were randomly sourced from 2021 to 2023, although this jumped to 72% in 2024. The jump in randomly sourced dogs in 2024 may reflect the recent increase in the number of companion animals being surrendered to shelters. Nonetheless, a deeper look at the 2024 dataset reveals that 77% of randomly sourced (shelter) dogs were used for educational purposes. In other words, shelter animals today in Canada are mostly used for education purposes (e.g., veterinary training).
Between 2021 and 2024, 31–37% of all purpose-bred dogs were exposed to the second-highest level of invasive research compared to 8–9% of all randomly sourced dogs. Similarly, between 2021 and 2024, 23–30% of all purpose-bred cats were exposed to the second-highest level of invasive research compared to 11–17% of all randomly sourced cats. No cats were exposed to the most invasive category of research from 2021 to 2024, while just under 1% of all dogs (still representing 70 to 94 individuals) were exposed to the most invasive protocols in 2021, 2023, and 2024 (no dogs were exposed to category E in 2022).
Cows
The use of cows in research saw its biggest jump after 2014, increasing 4 times between 2014 and 2017, from around 160,000 to over 600,000 individuals. Since then, the number of cows reported to the CCAC has fluctuated between approximately 370,000 and 645,000. The overall increase in the number of cows is likely due to interest in agriculture research, from both a production and welfare perspective.
Cows were almost never exposed to extremely harmful procedures in recent years: None of the cows reported to the CCAC from 2021 to 2023 were used in research causing severe pain (and less than 1% were in 2024); less than 1% were used in the second-highest level of invasive research from 2021 to 2024.
Pigs
Prior to 2011, pigs were rarely reported to the CCAC. However, their number increased over 300 times from 2010 to 2011, going from 183 to over 60,000. This jump is likely due to scientists genetically engineering them for biomedical and agricultural purposes. This number then dropped to under 38,000 around 2013 and has remained stable since. 97–99% of pigs reported to the CCAC from 2021 to 2024 were farmed pigs, with the remaining being minipigs (a specific small breed of pig used in biomedical research) and wild boars (studied in the wild as they’re considered invasive).
Pigs were rarely exposed to the highest level of invasiveness in Canada: in 2021 and 2022, it was under 1% of all pigs, but this increased to 7% of all pigs in 2023, and dropped again to less than 1% in 2024. Nonetheless, 15–22% of all pigs were exposed to the second-highest level of invasive research from 2021 to 2024, with 53–57% of this being basic research from 2021 to 2023 and 66% of this being medical research in 2024.
Amphibians & Reptiles
The number of amphibians used in research is higher than pigs, guinea pigs, cats, dogs, and rabbits, especially from the year 2000 and onwards. While overall usage of amphibians has increased, the number has fluctuated considerably between ~13,000 and ~115,000 since the late 1990s.
In contrast, reptiles have had a steady and low usage, especially from the 1980s to 2017 (around 11,000 or under). The number of reptiles reported to the CCAC reached its highest peak in 2024, at just under 28,000. This peak was likely due to research that used over 16,000 sea turtles (58% of all reptiles) for educational purposes (belonging to the least invasive research protocol).
From 2021 to 2024, frogs were the most common type of amphibian (72–83% of all amphibians), while turtles were the most common type of reptile (74–85% of all reptiles). 77–90% of all reptiles were used in protocols causing minor stress or pain of short duration between 2021 and 2023 — which dropped to 21% in 2024. In contrast, 47–66% of all amphibians were used in protocols causing minor stress or pain of short duration from 2021 to 2024. No reptiles were exposed to the highest level from 2021 to 2024, but close to 2% of all amphibians (all frogs) were used in the most painful protocols in 2024, with 75% of these being for regulatory testing.
Other Animals
The “other rodents” category includes squirrels, chipmunks, voles, hamsters, chinchillas, gerbils, and beavers, while the “other animals” category includes alpacas, bats, bears, coyotes, deer, ferrets, horses, octopuses, raccoons, sheep, whales, wolves, and more. Both of these categories likely include most animals reported to the CCAC who are studied in the wild as they’re not your typical research animal.
The number of “other rodents” has remained at a steady low rate throughout the entire time period observed (e.g., under 30,000 from 1985 to 2024). The number of “other animals” has fluctuated throughout, but has remained under 100,000 after 2010.
These types of animals were rarely exposed to research causing severe pain, ranging from 1–3% of all other rodents and 1% or less for all other animals between 2021 and 2024. More “other rodents” were used in protocols causing moderate to severe distress, ranging from 23–58% during the same time period compared to 8–16% of all other animals.
United States
Overall Use
Based on data from the USDA, the graph below shows animal use in science over time in the U.S., with different lines representing different animal categories, including total use. Please note that the USDA amended the “Other Animals” category in 2024, splitting it into “Other Farm Animals” and “Other Mammals,” while also adding “Birds,” which is why no data exist for these categories prior to 2024.
It cannot be emphasized enough: the majority of research animals are exempt from this dataset due to a lack of legal protections. With that caveat in mind, the use of regulated animals in science has been decreasing over time in the United States. The total number of animals reported to the USDA went from around 2 million in the 1980s and 1990s to just under 1 million since 2011. This is in sharp contrast to the use of 10 to 25 million rodents annually in the U.S., a conservative estimate, while others estimate the number to be over 100 million.
The decline in regulated animals in the U.S. could be due to one or more factors: 1) new scientific techniques that reduced or replaced animal use; 2) animal welfare concerns led to changes in regulations; 3) research became more expensive; and 4) pharmaceutical companies no longer depend on large numbers of animals for their drug discovery programs.
Indeed, when unregulated animals (such as mice and rats) are included, there is an upward trend in animal use, at least during a 15-year period (between 1997 and 2012), based on research fund data in the United States. Therefore, while regulated species are declining, they’re likely being replaced with unregulated species like rodents and fishes.
Rabbits
Rabbits are one of the most commonly reported animals in the USDA dataset, along with guinea pigs and hamsters, although their overall use has been decreasing over time (see the Rabbits section above for reasons why). Nonetheless, the use of rabbits is higher in the U.S. than Canada. For example, the number of rabbits reported to the USDA in 2024 was 29 times higher than the number reported to the CCAC (approximately 115,043 versus 3,992). From a per-capita perspective, the U.S. population is about 8.5 times higher than Canada’s, so this is a remarkable difference: after adjusting for population, the U.S. uses 3.4 times as many rabbits per capita as Canada.
Rabbits in the U.S. were also rarely used in the most painful protocols: 2% between 2021 and 2024. However, 30–36% of rabbits were subjected to the second-highest level during the same time period.
Guinea Pigs & Hamsters
Guinea pigs and hamsters are some of the mostly commonly reported animals to the USDA for animal use, although their overall number has been decreasing as well, likely due to mice replacing them as a preferred model. They were also the most commonly used animals in the highest pain category: 14–17% of all guinea pigs and 24–26% of all hamsters during the years 2021 to 2024.
Like rabbits, the use of guinea pigs is higher in the U.S. than Canada. For example, the number of guinea pigs reported to the USDA in 2024 was 16 times higher than the number reported to the CCAC (134,086 versus 8,205). Even after adjusting for population, the U.S. uses nearly twice as many guinea pigs per capita compared to Canada.
However, per-capita use of other rodents is higher in Canada relative to the United States. In Canada, hamsters are used so rarely that they’re categorized under “other rodents.” The absolute number of hamsters in the U.S. was approximately 6 times higher than the number of all other rodents in Canada in 2024 (72,443 versus 12,754). But, after adjusting for population, the U.S. actually uses fewer hamsters, roughly two-thirds of Canada’s rate.
Dogs & Cats
Like Canada, the number of dogs and cats used in science in the U.S. has dropped and has remained relatively low over the last 30 years compared to other animals (see the Dogs & Cats section above for reasons why), and more dogs than cats are used in research.
Both dogs and cats were rarely exposed to the most painful category of research: under 1% of all dogs and cats from 2021 to 2024. However, they were more likely to be used in the second-highest pain category: 27–31% of dogs and 31–37% of cats in the same time period.
Although more dogs and cats were reported in the U.S. in absolute numbers in 2024 compared to Canada (e.g., 42,880 dogs in the U.S. versus 9,252 dogs in Canada, and 12,004 cats in the U.S. versus 4,911 cats in Canada), these differences reverse when adjusting for population sizes. On a per-capita basis, the U.S. uses about half as many dogs and almost one-third as many cats as Canada.
Monkeys
The use of monkeys has been relatively low and stable compared to other species reported to the USDA, but there was a spike in the number of monkeys after COVID (see the Monkeys section above for more on this). For example, the number of monkeys increased more than 1.5 times during the years 2020 to 2022, going from around 68,000 to 113,500 during these years.
Monkeys were the most common animal reported in category B (animals held for breeding purposes or in a colony and not used for research purposes yet). From 2021 to 2024, 36–42% of all monkeys were not technically used in a study, but held in captivity. Moreover, monkeys were rarely exposed to the most painful protocols (approximately 1% from 2021 to 2024), although 22–24% of monkeys were reported in the second-highest painful category during the same time period.
Moreover, the use of monkeys is almost 13 times higher in the U.S. compared to Canada in 2024 (104,808 versus 7,826), and remains about 1.6 times higher after adjusting for population.
Farm Animals
The category “Farm Animals” represents pigs and sheep, who are also some of the least commonly reported animals to the USDA, and their use has also been decreasing over time (e.g., under 100,000 annually have been reported since 2013). In 2024, the USDA newly added “Other Farm Animals,” which presumably includes cows and chickens. However, as mentioned earlier, the number of farmed animals reported by agricultural research facilities are omitted by the USDA. So these estimates are very conservative as they exclude agriculture research, including studies on animal welfare and productivity.
Pigs and sheep were rarely exposed to the highest level of pain: 1–2% of pigs from 2021 to 2024, and less than 1% of all sheep. However, pigs and sheep were commonly used in the second-highest pain category: 66–71% of pigs and 49–62% of sheep during the same time period. Likewise, less than 1% of “Other Farm Animals” were reported in research causing the most pain in 2024, while 30% were reported in the second-highest pain category.
Other Animals
The category “Other Animals” (only used until 2023) and the new category “Other Mammals” (introduced in 2024) includes animals other than dogs, cats, monkeys, guinea pigs, hamsters, rabbits, pigs, and sheep. In other words, they include non-laboratory-bred rodents and fishes, in addition to a variety of wild animals like squirrels, bats, raccoons, bears, deer, wolves, skunks, dolphins, etc.
Similar to Canada, the number of “Other Animals” has fluctuated over the decades. Nonetheless, it’s important to note that the peak shown in 2020 might reflect differences in data reporting as 2020 was the only year where I manually obtained data from the USDA’s annual reports search, while data from 2021 to 2023 were obtained from APHIS annual summary reports. As mentioned previously, the annual reports omit non-protected species reported by agriculture research facilities from their final count and most animals reported in the “Other Animals” category in 2020 were from these facilities.
From 2021 to 2023, “Other Animals” was the second-most popular animal category reported in category B (animals held for breeding purposes or in a colony and not used for research purposes yet), accounting for 25–26% of animals. In 2024, the newly defined category “Other Mammals” showed a similar pattern, representing 22% of animals in category B. In contrast, a minority of “Other Animals” (3–4%) were used in the most painful protocols from 2021 to 2023, which was similar to “Other Mammals” in 2024 (5%). However, a larger proportion of these animals were reported in the second-highest pain category: 18–21% of “Other Animals” from 2021 to 2023 and 18% of “Other Mammals” in 2024. See Table 3 for details.
The USDA introduced a new category of “Birds” in 2024, but this excludes birds bred for research and by default farmed chickens used in agriculture studies (as the annual summary reports exclude agriculture research), so this new category presumably just tracks wild-caught birds. Most birds (89%) were reported in category C, which is research involving no pain. Indeed, only 1% and 5% of birds were reported in the highest and second-highest painful categories in 2024, respectively.
Key Takeaways
Prioritize species that are used in the most painful procedures (categories D and E), which include fishes, mice, hamsters, guinea pigs, rabbits, and pigs.
In Canada, fishes were the most frequently used animal in the most painful type of procedure from 2021 to 2024 (4–7% of all fishes: ranging from 64,000 to over 88,000 individuals), while mice were the most frequently used animal in the second-highest category of invasive research from 2021 to 2024 (62–69% of all mice: ranging from 700,000 to over 900,000 individuals).
It’s also likely these trends exist in the U.S., but fishes and mice are exempt from the USDA as these species aren’t protected under the AWA. Keeping this in mind, hamsters and guinea pigs were the most frequently used species in the most painful type of protocol in the U.S. between 2021 and 2024 (14–17% of all guinea pigs, ranging from 24,000 to over 34,000 individuals; and 24–26% of all hamsters, ranging from approximately 18,900 to over 26,000 individuals). Rabbits and pigs were also top contenders for animals used in the second-highest most painful protocols in the U.S. from 2021 to 2024: 30–36% of rabbits (ranging from approximately 35,500 to over 45,000 individuals) and 66–71% of pigs (ranging from approximately 32,100 to over 37,000 individuals).
Leverage the lack of human applicability in basic research to demand a phase-out of invasive procedures on these species.
In Canada from 2023 to 2024, 25–64% of salmon subjected to the most painful protocols (around 5,000 to 8,000 individuals), 68–78% of zebrafishes exposed to the second-most invasive protocols (around 50,000 to 66,000 individuals), and 57–59% of mice exposed to the second-most invasive protocols (around 410,000 to 430,000 individuals) were purposely put through stressful and painful procedures for the sake of basic discovery. This type of scientific discovery is hard to justify, so advocates can start here to ask for changes.
Leverage peaks of animal use to highlight opportunities for change.
The number of monkeys used in Canada for science reached its highest peak in 2023, which is tied to the demand of cynomolgus monkeys for COVID research — and the wildlife trafficking that ensued as a result of the heightened demand. With future pandemics likely, advocates can push for an end to wildlife trafficking of monkeys by demanding a ban on the importation of monkeys from countries with the highest exports, such as Cambodia. Advocates can also push to close loopholes that allow U.S. companies, such as Charles River, to obtain monkey samples from Canada, which may inadvertently increase the incentives for facilities in Canada to import monkeys.
Furthermore, monkeys were the most frequent type of animal to be stockpiled (i.e., not part of any active study) in the U.S. from 2021 to 2024. In other words, 36–42% of all monkeys reported to the USDA during this time period, ranging from 41,000 to over 44,000 individuals per year, were held in a facility but not used in any study. This type of captivity is hard for researchers to justify because keeping animals in captivity for breeding purposes goes against the “3 Rs” principle of animal research: it’s not reducing or replacing these animals, and there are major welfare (refinement) concerns when it comes to monkey confinement.
These welfare concerns are further compounded by government cuts to the USDA’s Animal and Plant Health Inspection Service, which has lost over one-third of its inspectors in recent years, leaving only about 77 individuals to oversee more than 17,000 facilities. This means that each inspector would have to inspect about 220 facilities per year in order to cover them all. Consequently, the welfare of these 44,000 stockpiled monkeys is likely going largely unmonitored, drastically increasing the risk of unchecked suffering.
Demand more transparency from these agencies, specifically calling for mandatory, publicly accessible, and species-specific data on all animal use.
For the CCAC in particular, better transparency would help explain what the undisclosed large-scale studies are that influence peaks for some species (e.g., almost 2.3 million chickens were used in one product development study in 2020, but no additional information was disclosed).
For the USDA, advocates can ask for full data disclosure, which means asking the USDA to stop excluding agricultural research animals from their official counts in the annual summary reports as that gives an incomplete picture of animal use, especially given the ties between animal agriculture and university-funded animal research. Similarly, U.S. advocates can demand that the AWA be updated to include protections for all vertebrates, including birds, rats, and mice — species that currently make up the vast majority of animals used but remain unprotected, and uncounted, under the law.
U.S. advocates should also recognize that the USDA is currently facing an impossible workload due to significant inspector shortages and new legal restrictions on enforcement. As such, demands for expanded protections must be coupled with calls to restore the agency’s oversight capacity to ensure these laws are actually enforced.
Expose this often-overlooked connection: animal agriculture and animal testing are deeply intertwined.
For instance, chickens were another group of animals that peaked in recent years in Canada, driven by massive industrial trials, such as one 2020 study that used nearly 2.3 million chickens. Such trends likely reflect the demands of agriculture research (such as animal welfare or productivity), and highlights the interconnection between animal agriculture and animal research. For example, the Canadian Poultry Research Council, which is composed of industry groups like Chicken Farmers of Canada, has committed $6 million to productivity and welfare research since its formation in 2001.
Advocates can broaden their impact by educating the public on how the agriculture industry utilizes the laboratory system to optimize production — often at the expense of animal welfare. Connecting these cause areas can also help the movement build a more unified front to challenge the commodification of animals across all industries. Not to mention, industry funding can become problematic when industry-funded professors shape public opinion and policy to benefit animal industries, which has been observed in the U.S. for animal agriculture sustainability research.
Point to the stark difference between U.S. and Canadian animal research use to pressure policymakers to reduce animal use.
While absolute animal use is often higher in the U.S. than in Canada, several key species remain substantially higher in the U.S. even after adjusting for population size. For example, in 2024, the U.S. used around 115,000 rabbits while Canada used just less than 4,000 — a 29-fold difference in absolute numbers that translates to more than three times higher per-capita use in the United States. Similar population-adjusted gaps persist for guinea pigs and monkeys. At the same time, population-adjusted comparisons show that Canada has higher per-capita use of certain species, including dogs, cats, and some rodents.
Such comparisons demonstrate how advocates in both countries should use population-adjusted benchmarks when engaging with policymakers. In the U.S., comparisons with Canada demonstrate that substantially lower per-capita use is achievable for species such as rabbits, guinea pigs, and monkeys. In Canada, higher per-capita use of dogs, cats, and certain rodents (e.g., hamsters) points to opportunities for targeted reductions. The messaging in both countries should be framed around how lower use is not only possible, but already being done by a peer nation with similar scientific goals.
Feel emboldened by the fact that public opinion is on your side.
Only 47% of people in the U.S. view medical testing on animals as morally acceptable — a significant drop from nearly 65% in 2001. Furthermore, 85% of U.S. adults have agreed that “animal experimentation should be phased out in favor of more modern research methods.” Similarly, in Canada, the demand for accountability is overwhelming: 83% of Canadians believe institutions should be more transparent about their animal use, and 82% support mandatory ethical oversight.
When speaking to policymakers, advocates can cite these polls to demonstrate that the existing lack of transparency and legislative inaction not only harms animals but also disregards the values of the tax-paying public.
Conclusion
While some progress has been made in promoting non-animal alternatives, the continued reliance on animals — often with limited transparency — underscores the need for stronger advocacy and policy reform in Canada and the United States. A closer look at the data makes these shortcomings clear: certain species are disproportionately subjected to the most painful procedures, basic research contributes to a large volume of animal research, and oversight from both the CCAC and the USDA leave major gaps in accountability. By focusing on the species and procedures where harm is most concentrated, and by demanding transparency, advocates in both Canada and the U.S. can push for meaningful reductions that are both scientifically defensible and publicly supported.
