Animal Welfare

Cloning is an incredibly inefficient technology that results in a tremendous loss of animal life. From grossly oversized heads, twisted limbs, and bloated fetuses to malformed kidneys, immune system deficiencies, and respiratory distress, cloned animals and their surrogate mothers suffer from any of a variety of severe health problems, abnormalities, and deformities that are seen only rarely otherwise.

According to researchers, the problems that plague animals involved in the cloning process “create serious animal welfare concerns that limit the acceptability and utility of the present technology."[1] Indeed, experts at the European Food Safety Authority concluded that "The health and welfare of a significant proportion of clones has been found to be adversely affected,"[2] and the European Group on Ethics concluded that, “Considering the current level of suffering and health problems of surrogate dams and animal clones,” they could find no ethical justification for cloning animals for food.[3]

Some of AAVS’s main concerns are listed here:
  • Despite years of research, more than 95 percent of cloning attempts fail. A significant number of cloned animals, as well as surrogate mothers who carry clone pregnancies, suffer serious and painful diseases and deformities to produce each ‘successful’ clone.
  • Seemingly healthy cloned animals have been known to unexpectedly and suddenly develop health problems later in life.
  • There is little rigorous scientific data available to make any claims about the health of the offspring of cloned animals, but the few studies that have been done indicate that these animals are weaker and less likely to survive than their conventional counterparts.
  • Cloning increases the commodification of animals and promotes intensive farming practices, which negatively affect animal welfare at a time when consumers are increasingly demanding that farmed animals be treated more humanely.
  • The FDA’s assessment of animal health risks was highly flawed and scientifically unsound. The government should not lift the moratorium on animal cloning until the animal welfare problems associated with cloning are thoroughly considered and properly addressed.
  • AAVS believes that the animal welfare and ethical costs of cloning make the technology a deplorable way to produce animals and should be prohibited.

Additional details about animal welfare and cloning, as well as links for further reading, are provided below.

Success rate

Only a very small percentage of cloned embryos—typically zero to three percent—will be successfully delivered,[4] usually by cesarean section. Of those who are born, only a relatively small percentage are healthy enough to live for more than a few days or weeks.[5,6]

To produce the first cloned animal, for example, 277 cloned embryos were implanted, only 13 pregnancies resulted, and only 1 animal was born successfully: Dolly, the now infamous sheep.[7] In a Texas A&M bovine study, 17 percent of 322 somatic cell nuclear transfers developed into embryos (roughly 54), of which 26 were successfully implanted. After 40 days of pregnancy, six fetuses survived. After 290 days, only one survived. This calf had significant metabolic and cardiopulmonary abnormalities similar to those seen in previous studies, diabetes mellitus, and was susceptible to severe immune-system deficiencies.[8] According to a recent 2007 study,[9] 18 percent of cloned calves died at birth, and 32 percent of cloned calves who survived birth in another study died within the first month.[10]

Even the cloned animals who survive the neonatal period have been known to suffer unexpected health consequences later in life. In fact, an article published by a leading cloning researcher in The New England Journal of Medicine stated that, “given the available evidence, it may be exceedingly difficult, if not impossible, to generate healthy cloned animals....”[11]

With such low success rates, not only do the cloned animals endure suffering, but so do hundreds of additional animals as they are pumped with hormones and their eggs harvested, or as they are implanted with embryos, often repeatedly, in an attempt to produce just one cloned animal who survives.

Surrogate mothers and their fetuses

According to the FDA’s assessment of animal cloning risks, abnormal fetal development is common in clones, which translates into abnormal pregnancies with a host of complications that threaten the lives of the unborn clones and their surrogate mothers.[12, 13]

A set of typically fatal conditions known as hydrops, for example, in which the mother and/or the fetus swells with fluid to the point of looking like she is about to burst, occurs frequently in clone pregnancies. From the data presented by the FDA, hydrops has occurred in 28 percent of cow clone pregnancies, with one study (conducted by Cyagra, a biotech company leading the push for cloned foods) reporting hydrops in over 50 percent of cases.[14] In contrast, hydrops occurs rarely or never in pregnancies produced through artificial insemination or natural breeding.[15]

Clone pregnancies are also associated with a greater risk of late term loss, with roughly 45 percent of pregnancies reported lost in the second or third trimester in studies at a research farm in France.[16] Such losses, normally uncommon in conventional pregnancies, “expose the recipients [surrogates] to conditions that threaten their welfare.”[17]

In the relatively few cases when a cloned fetus is carried to term, dystocia (painful labor) and intervention for delivery is far more likely in a clone pregnancy than a more conventional pregnancy. Fifty-four percent of surrogate mothers in the Cyagra study[18] required a cesarean section for delivery, with an additional 30 percent requiring non-surgical intervention, whereas less than one percent of artificially inseminated females from another study[19] required such surgery.

Cloned newborns

Based on published data and the FDA’s own report, cloned animals suffer from respiratory distress; hypoglycemia; weakened immune systems; developmental problems; deformities including squashed faces, contracted tendons, and limbs that bend the wrong way; malformed livers, kidneys, or hearts; and a variety of ailments that claim the lives of approximately one-third of neonates.[20]

According to the recent study conducted by Cyagra, 37 percent of cloned calves who survived birth had enlarged umbilical cords, a condition that often requires surgery; 19 percent had respiratory problems; 20 percent exhibited signs of depression; 17 percent were hyper- or hypothermic; and 75 percent required antibiotics.[21] Almost half of the cloned animals who survived birth died within the first five months, despite access to extensive veterinary care, and despite the fact that any of more than 10 different interventions were performed.

Many of these ailments are related to Large Offspring Syndrome (LOS), a commonly observed problem with cloned animals in which the animal develops to be significantly bigger at birth than a conventional animal. It is not uncommon for the animal to be twice normal size, and in one study, a lamb was reported as being five times larger than normal.[22] In fact, LOS occurred in over 50 percent of calf clones included in the FDA’s report, compared to 6 percent of conventionally bred animals.

In addition to the problems caused to the cloned animals, LOS also results in an overly painful and stressful labor and delivery for the mother, often requiring surgical intervention to deliver the baby. In one published study, three of 12 surrogate mothers died during pregnancy as part of a cattle cloning project.[23]

Even the few cloned animals who live for longer than 6 months and appear otherwise healthy have been known to suffer unexpected health consequences later in life. Studies in cows, for example, have documented cases of sudden, unexplained deaths and subclinical pathologies that had gone undetected.[24] Data from the FDA’s risk assessment also reveal that the reproductive performance of cloned animals, as measured by sperm characteristics, ejaculate volume, rate of pregnancy, and rate of abortion, may be impaired. There is little data on the health of older cloned animals.

Offspring of cloned animals

There is little data available on the health of the offspring of cloned animals. There are a few anecdotal reports and some data, primarily from cloning companies, regarding the health of a small number of individuals from only a handful of clones. While the offspring of clones appear to have fewer problems than clones, they are less likely to survive than conventional offspring and there is some evidence that these animals are still not normal.[25]

However, it is likely to be the offspring of clones who initially enter the food supply. Since there can be no offspring of clones without an initial cloning event, the animal welfare concerns that apply to cloned animals extends to the production of their offspring as well.

Cloning compared to assisted reproductive techniques

As indicated by the data discussed above, the animals involved in the cloning process are tremendously more likely to suffer from a variety of severe health problems and die prematurely than animals produced through conventional assisted reproductive technologies (see graph below).

Given such evidence, it is clear that cloning raises troubling new concerns about animal welfare, and that cloning is not an acceptable way to produce animals.

Industrial farm animal production

Cloning is often pursued in order to aid in the intensive production of livestock—to produce animals who grow faster so they can be slaughtered sooner, and to raise more animals in a smaller space. The rise of 'factory-farming' has already led to serious animal health problems, including animals who grow so big so quickly that their bones break, and animals who are confined to spaces so small they cannot even turn around or stretch. Moreover, the industrialization of agriculture has driven many small farmers out of business, concentrating operations to only a handful of large corporations that are willing to sacrifice welfare and sustainability for profit.

To use cloning, with all of the animal suffering that it entails, to further commodify animals and make them mere machines of manufacture is a major affront to animal welfare.[26]

FDA Risk Assessment

With more than 95 percent of cloning attempts regularly causing death or severe health problems for cloned animals and their surrogate mothers, there is widespread recognition in the scientific and medical communities that cloning presents serious risks to the animals involved.[27, 28, 29, 30] Yet the FDA has repeatedly glossed over the animal welfare problems raised by animal cloning. In its risk assessment on cloned foods, the FDA dismisses any concerns by asserting that cloning poses no “unique” risks to animal health that are not seen with the assisted reproductive technologies already practiced by many large-scale livestock operations.[31]

In making such a flawed assessment, the FDA has completely ignored the tremendous increase in frequency with which animal health risks occur as a result of cloning (see graph). As described above, one out of every two, three, or four animals involved in the cloning process suffer from serious health problems that are rarely seen otherwise. The FDA can attempt to mask the issue by saying no new problems arise from cloning, but no risk assessment can be considered complete without considering how often these problems are likely to occur.

The FDA attempts to further dismiss the animal health problems caused by cloning by stating that the technology is improving with time. However, the data do not support such a statement, and, to the contrary, indicate that there have actually been no significant improvements. Rudolph Jaenisch, a prominent cloning researcher at MIT, has been quoted as saying, “There’s been no progress. I mean it. Zero. The only thing we’ve begun to realize is how big the problem is.”[32] Another leading cloning researcher, Peter Mombaerts from Rockefeller University, has stated that his best hopes for an “extremely efficient” version of cloning would have only a 20-30 percent success rate.[33]

In addition, it would involve tremendous animal suffering, as well as a significant amount of animal lives, time, money, and effort to achieve any meaningful improvements in cloning. Such costs are unjustifiable when there is little benefit or demand to clone animals.

Our government must take a hard look at the animal welfare and ethical implications of animal cloning before allowing this technology to move forward. In doing so, it should be clear that it is unjustifiable to clone animals for food.



[1] Ortegon, H., Betts, D.H., Lin, L., Coppola, G., Perrault, S.D., Blondin, P., et al. (2007). Genomic stability and physiological assessments of live offspring sired by a bull clone, Starbuck II. Theriogenology, 67(1), 116-126..

[2] European Food Safety Authority (2008). Draft Scientific Opinion on Food Safety, Animal Health and Welfare and Environmental Impact of Animals derived from Cloning by Somatic Cell Nuclear Transfer (SCNT) and their Offspring and Products Obtained from those Animals.

[3] The European Group on Ethics in Science and New Technologies to the European Commission (2008). Opinion No. 23 Ethical aspects of animal cloning for food supply.

[4] Paterson, L. (2002). Somatic Cell Nuclear Transfer (Cloning) Efficiency. Roslin Institute.

[5] Paterson, L., DeSousa P., Ritchie W., King T., and Wilmut, I. (2003). Application of reproductive biotechnology in animals: Implications and potentials. Animal Reproduction Science, 79(3-4), 137-143.

[6] Wilmut, I., Beaujean, N., de Sousa, P.A., Dinnyes, A., King, T.J., Paterson, L.A., et al. (2002). Somatic cell nuclear transfer. Nature, 419, 583-587.

[7] Begley, S., et al. (1997, March 10). Little Lamb, Who Made Thee? Newsweek, 52.

[8] Hill, J.R., Winger, Q.A., Long, C.R., Looney, C.R., Thompson, J.A., and Westhusin, M.E. (2000). Development rates of male bovine nuclear transfer embryos derived from adult and fetal cells. Biology of Reproduction, 62, 1135-1140.

[9] Panarace, M., Agüero, J.I., Garrote, M., Jauregui, G., Segovia, A., Cané, L., et al. (2007). How healthy are clones and their progeny: 5 years of field experience. Theriogenology, 67(1), 142-151.

[10] Chavatte-Palmer, P., Remy,D., Cordonnier, N., Richard, C., Issenman, H., Laigre, P., et al. (2004). Health status of cloned cattle at different ages. Cloning and Stem Cells, 6(2), 94-100.

[11] Jaenisch, R. (2004). Human Cloning—The Science and Ethics of Nuclear Transplantation. New England Journal of Medicine, 351, 2787-2791.

[12] Food and Drug Administration (2006). Animal Cloning: A Draft Risk Assessment, 107-116.

[13] See also: Heyman, Y., Chavatte-Palmer, P., LeBourhis, D., Camous, S., Vignon, X., and Renard, J.P. (2002). Frequency and occurrence of late-gestation losses from cattle cloned embryos. Biology of Reproduction, 66, 6-13.

[14] Panarace, et al. (2007). See note 9.

[15] FDA (2006); Panarace, et al. (2007). See notes 12 and 9.

[16] Heyman, et al. (2002). See note 13.

[17] Chavatte-Palmer, et al. (2004). See note 10.

[18] Panarace, et al. (2007). See note 9.

[19] Kruip, Th.A.M., & den Daas, J.H.G. (1997). In vitro produced and cloned embryos: Effects on pregnancy, parturition and offspring. Theriogenology, 47, 43-52.

[20] Vajta, G., & Gjerris, M. (2006). Science and technology of farm animal cloning: State of the art. Animal Reproduction Science, 92, 211-230; FDA (2006), 116-127. See note 12.

[21] Panarace, et al. (2007). See note 9.

[22] Young, L.E., Sinclair, K.D., and Wilmut, I. (1998). Large Offspring Syndrome in cattle and sheep. Review of Reproduction, 3, 155-163.

[23] Turner, J. (2002). The Gene and the Stable Door: A Report for the Compassion in World Farming Trust.

[24] FDA (2006), 127-135, 147-149. See note 12.

[25] FDA (2006). See note 12.

[26] Turner, J. (2002). See note 23.

[27] Ortegon, et al. (2007). See note 1.

[28] Heyman, Y., Chavatte-Palmer, P.,Berthelot,V., Fromentin, G., Hocquette, J.F.,Martignat, L., and Renard, J.P. (2007). Assessing the quality of products derived from cloned cattle: An integrative approach. Theriogenology, 67(1), 134-141.

[29] Chavatte-Palmer, et al. (2004). See note 10.

[30] Jaenisch, R. (2004). See note 11.

[31] FDA (2006). See note 12.

[32] Meek, J. (2002, April 19). Tears of a clone. The Guardian. Retrieved Dec. 2006, from,2763,686989,00.html.

[33] Gardner, A. (2007, February 12). Scientists clone mice from hair follicle stem cell. Washington Post. Retrieved Feb. 2007, from

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