Cloning: What We’ve Learned

There are more than 40 live cloned horses. What have we learned and what concerns do we have?
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The first equine clones were born in 2003, and now advertisements for cloning can be found in equine magazines, and the AQHA has considered registering cloned foals. There are more than 40 live cloned horses. What have we learned and what concerns do we have?

Foal Health Cloned foals do not seem to suffer the same abnormalities seen in cloned calves and lambs, in which “large offspring syndrome” results in oversized animals and organ system problems.

Our laboratory at Texas A&M has reported on the health of the 14 live foals we have produced. About half of the cloned foals had some issues at birth; the major problems were weakness and maladjustment, contracted tendons in the front legs, and enlarged umbilical remnant, some of which required surgical removal. Two of the foals died, one from pneumonia and one from complications after anesthesia. The remaining foals resolved their problems within a few weeks. Aside from one foal that had bladder stones in its first year, to our knowledge all cloned horses are currently healthy.

What is causing problems with cloned foals at birth? Most likely differences in gene expression (how the genes are being used) in the cloned foals. During cloning, the DNA of a skin cell from the donor animal is placed in a host egg (oocyte). The oocyte has to change all the “on/off” instructions attached to this DNA so the DNA can start to express the appropriate genes to make an embryo

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Written by:

Katrin Hinrichs, DVM, PhD, Dipl. ACT, is a professor and the Patsy Link Chair in Mare Reproductive Studies in the Department of Physiology and Pharmacology at Texas A&M’s College of Veterinary Medicine and Biomedical Sciences.

2 Responses

  1. re: Cloning: What We’ve Learned

    We are playing GOD. First animals and then humans. This is not right.

    You will have many more problems down the line when we get more and more cloning. Who is going to be keeping tract?

  2. re: Cloning: What We’ve Learned

    cloning then does not really produce a replica of the original animal there are mitochondrial DNA differences etc. I as a breeder have concerns. I hope the AQHA takes a very long look at this as our horses are being DNA typed and parentage verified, th

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