Animal Eugenics: For Better or For Worse


                      By Michael W. Fox


Eugenics is a term with negative connotations and has been considered an exclusively human process. But in fact, it has been the driving ethos behind the domestication of animals for millennia to primarily improve their utility for various purposes of human use through selective breeding. Extending the controversial concept of eugenics to examining the selective breeding of animals and more recent biotechnologies of genetic engineering, cloning and gene-editing may lead to establishing bioethical standards to better insure the health and well-being of animals under human dominion.


Eugenics, defined as the study of how to arrange reproduction within a human population to increase the occurrence of heritable characteristics regarded as desirable fell into disrepute after its surgency in America in the 1930s which Adolph Hitler sought to emulate. Proposed by Sir Francis Galton as a method of improving the human race, (1) eugenics was increasingly discredited as unscientific and racially biased during the 20th century. During the American eugenics movement in the 1920s and 1930s laws were enacted that legalized forced sterilizations and prohibited individuals that had mental or physical defects and couples of mixed-race from marrying.

One significant definition of this term “bringing about improvement in the type of offspring produced” (Random House Dictionary of the English Language, 1966) clearly implies that eugenics can be applied to species other than human. I have had concerns for decades about human manipulation of animals at the genomic level for various purposes, which may not actually benefit the animals themselves.


There is in urgent need of veterinary bioethical consideration (2) and application of eugenics to eliminate heritable diseases and extreme physical anomalies such as brachycephaly in dogs and cats and now even horses. Eugenics is called for in this domain because of what humans have done to selected animals that is detrimental to their health and well-being. There is public resistance in part because of the abhorrent history of its application to humans, which is most regrettable. Domestic animals should not suffer as a consequence of being born with human-selected abnormalities, no matter how “appealing” like the large domed heads of brachycephalic dog and cat breeds. Public resistance to critically assessing such creations may in part be based on avoiding showing prejudice and discrimination between the unhealthy and abnormal and the healthy norm.

Norway has passed legislation prohibiting the breeding of English bulldogs and Cavalier king Charles spaniels because of concerns about health and welfare. (3,4).Prospective purchasers of genetically anomalous pets can exercise due caution and consider not purchasing such animals as an ethical act of eugenics in opposition to such animal exploitation. Similarly, many breeders and dog breed clubs, with the support of veterinary specialists and geneticists, are engaging in the eugenics of genetic screening and progeny testing as well as outbreeding where feasible to remove deleterious inherited traits in their animals and so-called genetic bottlenecks. (5).

The eugenics ideology of genetic determinism helped fuel the pet cloning business. One company in this business states “Your pets clone will have the exact same genetics as your original pet. The clone will therefore have the same genetic coding to result in the same appearance and temperament as your original pet. The clone will literally be the closest possible genetic replica of your original pet, as they will both have exactly the same DNA! They are essentially twins that are born at different points in time.” (6). But because of epigenetic influences cloned deceased animals were never identical, especially behaviorally, to the original animals. (7,8). One must also consider the treatment of surrogate animals implanted with their own eggs that contain the activated cells of deceased pets, and the ethics of such applied eugenics.

The recent eugenics imitative of gene editing by a Chinese scientist of human twins to give them immunity to the HIV virus which their offspring would inherit caused international consternation about possible harmful (multiple pleiotropic and epigenetic) consequences to these children (9). When it comes to other species, however, eugenics is rarely questioned when there are promised human benefits.


Eugenics is in urgent need of application in the poultry and livestock industries where commercial varieties of poultry, pigs and cattle have been selectively bred for rapid growth or high productivity which can be detrimental to their health and well-being. (10)

Eugenics has been practiced by many zoos over the past few decades to avoid inbreeding of captive species by trading unrelated animals from zoo to zoo and replenishing with animals from the wild, which is not without bioethical consideration. So-called genetic bottle-necks from reduced genetic diversity can lead to extinction in both captive and wild populations. Lack of genetic diversity can mean reduced fertility and resistance to diseases. Poor resistance, attributed to lack of genetic diversity, to mycoplasma infections transmitted from more resistant ranched cattle is currently an emerging disease decimating American buffalo. (11).


Eugenics is being pursued by various vested interests using the new tools of genetic engineering, cloning and gene editing (CRISPR technology) to increase the productivity and disease resistance of farmed animals. Supporters of gene-editing liken it to natural mutations mimicking natural selection and preferable with greater precision than genetic engineering which involves inserting other species’ DNA. Recent examples of gene-edited animals include super-muscly cows and pigs, hornless cattle, chickens and pigs made to resist certain diseases, cows with human genes, and other genetic experiments creating animals for biomedical models of human diseases. (12, 13, 14, 15).

CRISPR gene editing has been found to unintentionally cause changes in gene regulation. Gene-edited hornless cattle have unexpected antibiotic resistant genes, despite researchers’ original claims that they did not contain any genetic errors. (16). Further evidence of the limitations of genetic determinism and its eugenics application come from our lack of complete understanding of genomics which artificial intelligence may never provide sufficiently override the precautionary principle. For instance, an experiment on hamsters subjected to CRISPR specifically targeted gene editing to make them less aggressive actually made them more aggressive. (17). Using CRISPR-Cas9 to disrupt Fel d 1 genes in cats to make them hypoallergenic to humans will not, hopefully, have unforeseen consequences ( 18).

China’s researchers have created a long list of CRISPR firsts in monkeys, dogs, mice, rats, pigs, and rabbits. This research promises higher quality meats, disease-resistant livestock, and new medical treatments and organs for human transplantation. So far, many of the animals created are simply proofs of concept but gene engineers claim to have created monkey models of muscular dystrophy and other degenerative neurological diseases, autism, and cancer (19).

CRISPR technology has allowed the idea of gene drives to be realized. These are designed to ‘drive’ modified genes in altered animals into wild populations to enforce their own propagation to all offspring, circumventing the rules of natural inheritance. Examples under investigation are malaria mosquitoes modified to breed only males and thus die out, invasive mice similarly modified to die out and mice modified to prevent their ticks conferring Lyme disease to humans. However, many claimed features of gene drives are unrealistic and carry a high degree of scientific uncertainty and unpredictability. (20).

There are virtually no bioethical constraints on such activities which enjoy government support in many countries. Labeling of produce from such animals to inform consumers is unlikely, and like genetically engineered crops are considered “Substantially equivalent” to produce from conventionally bred animals by regulatory authorities. While there is a ban on the commercialization of gene-edited crops and animals in the European Union, Great Britain has announced the Genetic Technology (Precision Breeding) Bill “to remove unnecessary barriers inherited from the EU to enable the development and marketing of precision-bred plants and animals, which will drive economic growth and position the UK as the leading country in which to invest in agri-food research and innovation.” (21). Critics are concerned that gene-edited farm animals will be kept under intensive, confinement conditions with this technology being used to help prevent “domestogenic” diseases created by selective breeding and by conditions in which they should not have been put in the first place. (22).


In sum, applying eugenics to animals for some alleged greater good must be subject to bioethical evaluation in every instance, considering the health, well-being and rights of each and every individual subjected to such treatment as well as the environmental/ecological, gene-pool, natural biodiversity and public health consequences. Perhaps if there were greater concern amongst the scientific community and an informed public over gene editing of non-humans equaling that expressed over gene editing of humans, we might indeed see greater progress for the common good and the good of the commons.


1.Gillham NW. Sir Francis Galton and the birth of eugenics. Annu Rev Genet. 2001: 35;83-101. doi: 10.1146/annurev.genet.35.102401.090055. PMID: 11700278.

2.Fox MW. Veterinary Bioethics. J Am Vet Med Assoc.1996: 208;1628-1629.

3.Jarvis S. Banning breeds: help or hindrance? Veterinary Record. 2022:190; 139

4.Loeb J. Will breed ban result in rise of illegal activity? Veterinary Record, 2022: 190; 140.

5.Pedersen NC, Pooch AS, & Liu H. A genetic assessment of the English bulldog. Canine Genet Epidemiol 2016:3;6

6. 5/25/22

7.Bondriansky R. Why Barbra Streisand’s cloned dogs aren’t identical to the original pet by The Coversation, 2018.March 1,

8.Murphy B. Few replicas as first cloned cat nears 10. 2011.Phys Org August 8

9.Normile D. CRISPR bombshell: Chinese researcher claims to have created gene-edited twins 2018..26 Nov . Science. Error! Hyperlink reference not valid.

10.Cheng H-W. Breeding of tomorrow’s chickens to improve well-being. Poultry Science 2010: 89: 805-813

11.USDA. Mycoplasma bovis. An Emerging Pathogen in Ranched Buffalo. Accessed May 25, 2022

12.Singh P, Ali SA. Impact of CRISPR-Cas9-Based Genome Engineering in Farm Animals. Vet Sci. 2021:8;122. doi:10.3390/vetsci8070122

13.Khwatenge C N and Nahashon SN. Recent Advances in the Application of CRISPR/Cas9 Gene Editing System in Poultry Species. 19 February 2021 Front. Genet. doi: 10.3389/fgene.2021.627714

14.Perisse IV Fan Z, Singina, GN. et al. Improvements in Gene Editing Technology Boost Its Applications in Livestock. Front. Genet. 2021 January 8.doi: 10.3389/fgene.2020.614688

15.Chenouard V, Remy S, Tesson L. et al, Advances in Genome Editing and Application to the Generation of Genetically Modified Rat Models. Front. Genet 2021 April 20.. doi: 10.3389/fgene.2021.615491

16.Norris AL, Lee SS, Greenlees KJ, et al. Template plasmid integration in germline genome-edited cattle. Nat Biotechnol. 2020:38;163-164. doi: 10.1038/s41587-019-0394-6. Epub 2020 Feb 7. Erratum in: Nat Biotechnol. 2020 Mar 5;: PMID: 32034391.

17.Taylor JH., Walton JC., McCann, KE. et al CRISPR-Cas9 editing of the arginine–vasopressin V1a receptor produces paradoxical changes in social behavior in Syrian hamsters. PNAS 2022:119(19)e2121037119

18.Brackett NF, Davis BW. Adli M. et al, The CRISPR Journal. Apr 2022.213-223.

19.Cohen J. China’s CRISPR push in animals promises better meat, novel therapies and pig organs for people. Science, 2019 July 31. .

20.Committee on Gene Drive Research in Non-Human Organisms: Recommendations for Responsible Conduct; Board on Life Sciences; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and Medicine. Gene Drives on the Horizon: Advancing Science, Navigating Uncertainty, and Aligning Research with Public Values. Washington (DC): National Academies Press (US); 2016 Jul 28. See also,

21.Jarvis S. Editorial: Debating the ethics of gene editing. Veterinary Record 2022:190; 387

22.Fox MW, Farm Animals: Husbandry, behavior and veterinary practice. 1984. Baltimore MD University Park Press. p157-160