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Convention on Biological Diversity (1992) to promote biodiversity, the ethical imperative to do so by subjugating the welfare of individual animals to the desire to preserve an equine breed is unconvincing.
Are there welfare-based reasons which make animal cloning unethical?
Current cloning techniques result in recognised welfare problems (Renard et al. 2001; Houdebine et al. 2008; Anon 2012b; Kim et al. 2012, 2014). Problems associated with cloning across a variety species, but particularly cattle, include placental abnormalities during pregnancy, fetal abnormalities, dystocia related to ‘large offspring syndrome’ in farm animals, neonatal weakness/disease, systemic illness/ disease in cloned animals and premature ageing of adult clones (Kuhholzer-Cabot and Brem 2002; Chavatte-Palmer et al. 2003; Loi et al. 2006; Arnold et al. 2008; Houdebine et al. 2008; Jang et al. 2010; Anon 2012b). One of the prime factors behind the European
Commission’s decision in late 2013 to propose a ban on the cloning of food animals (
http://europa.eu/rapid/press- release_IP-13-1269_en.htm. Accessed 20.03.14) and the recent European Parliament decision to extend that ban (Anon 2015) is the fact that farm animal cloning is viewed as a risk to animal welfare (Gamborg et al. 2005). This was made clear by Renate Sommer, German MEP, who stated that the prohibition was based in concerns about ‘the negative effects on animal welfare’ and that ‘prohibiting cloning is a matter of European values and principles’ (Anon 2015). If concerns about the health and welfare of clones and their dams provide a convincing ethical argument against cloning of farm animals, does the same argument apply to horses? Data about the health and welfare of equine clones is
comparatively lacking. Only the groups led by Katrin Hinrichs in the USA (Hinrichs 2006; Johnson et al. 2010) and Cesare Galli in Italy (Galli et al. 2003; Lagutina et al. 2005) have published data on their success rates and on problems associated with current cloning techniques. These data are reviewed in the next few paragraphs.
Embryo loss in equine cloning Hinrich’s group (Johnson et al. 2010) reported that 26% of cloned embryos transferred by them resulted in the birth of a live foal, whereas Galli and coworkers reported that three live foals resulted from transfers of more than 100 cloned embryos (Galli et al. 2003; Lagutina et al. 2005). In a retrospective study of all nuclear transfer derived embryos at Texas A&M University from 2004 to 2007, Johnson et al. (2010) found that 81% of oocytes which had been subjected to nuclear transfer cleaved after activation. Of those cleaved embryos, 5% developed to blastocyst stage. A total of 51% of those blastocysts, having been transferred, resulted in the establishment of pregnancy in the recipient mare, as determined by ultrasonography at 11–16 days post ovulation.
Fetal abnormalities The only data available on fetal losses and abnormalities comes from Hinrich’s group (Johnson et al. 2010). A total of six pregnancies were lost between 3 and 9 months of gestation and one recipient mare developed a neurological condition and was subjected to euthanasia. The cause of the
neurological condition was not discovered and her fetus was normal. A total of three fetuses were aborted between 5 and 9 months; one had no abnormalities, one had no detectable abnormalities (it had been scavenged) and one had an umbilical hernia (omphalocoele). One foal was born prematurely and died.
Dystocia Data about dystocias in horses is also sparse. Johnson et al. (2010) reported that one mare had a dystocia which required caesarean section at full-term and a dead foal with severe contraction of the forelimbs and an omphalocoele was delivered. A total of 14 of 31 mares which were pregnant between 11 and 16 days post ovulation delivered live foals and 13 were born at normal gestational length. None was oversized or overweight in comparison to the mare and all mares had uncomplicated foalings. One had a prolonged gestation, but was nonetheless born small and underweight; however, at a year of age, its weight was comparable to that of the other surviving foals.
Neonatal health In the study of Johnson et al. (2010), two foals had signs of hypoxic ischaemic encephalopathy at birth, but recovered with treatment. Two foals died shortly after birth, one from pneumonia and one following anaesthetic complications during an attempt to surgically correct a perceived bladder abnormality. A total of 7 of 14 foals required administration of supplementary oxygen for >12 h after birth, one for 15 days. All foals were treated as ‘high risk’ and given antibiotics after birth. A total of 8 of 14 foals required antibiotics for more than 5 days. Half of the foals had some form of umbilical abnormality, 8/14 had some form of flexural or angular limb deformity (all corrected by 6 months) and 2/14 exhibited incomplete ossification of the cuboidal bones. On average, foals required 8.5 days of intensive care following birth. Those which survived a week grew and developed normally thereafter, apart from one foal which required two surgeries to remove uroliths (bladder stones). Of the three foals produced by Galli and coworkers (Galli et al. 2003; Lagutina et al. 2005), one died from septicaemia and the other two were reported as being healthy. It is clear that the evidence base about health and
welfare issues associated with cloning using SCNT is much less robust for horses than for farm animal species. The broad summary from the little data available seems to be that equine cloning is associated with high rates of embryonic loss; some incidence of fetal abnormalities (although this appears to be lower than that recorded in farm animals) and a requirement for neonatal intensive care. In contrast to farm animals, dystocia attributable to oversized fetal clones does not seem to be a significant problem in horses. Similarly, the problems of hydrops of the fetal membranes which occur in cloned cattle seem not to occur in mares, possibly due to differences in placentation. It is difficult to know whether some abnormalities in neonatal and foal clones, for example limb deformities, are truly attributable to the cloning process, because such problems are not uncommon in foals anyway. To date, there have been no long-term studies on the health and welfare of cloned horses. Further research is clearly needed to increase the
evidence base on the short, medium and long-term health and welfare effects of equine cloning. Until such evidence is
©2016 TheAuthors EquineVeterinaryEducationpublishedby JohnWiley&Sons Ltdonbehalf of British EquineVeterinary Association
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