Genetic Engineering in Animals


Genetic Engineering in animals is a broad topic. This includes all types of manipulation of the genetic code of animals of any species or complexity. By this definition genetic engineering of animals has been taking place for thousands of years in the form of selective breeding. Humans have chosen which characteristics they liked in an animal be it for appearance, ability to survive, etc. Humans have then breed these animals in a variety of ways. If all these forms of breeding were considered genetic engineering this would be a never ending topic. This page will cover the technological side of genetic engineering of animals. The new advancements and the ethics behind those advancements.

There are three types of "modern" genetic engineering that can be used on animals. Modern being the use of chemicals instead of just selective breeding.

Xenografting-The use of human DNA to supplement an animal's or vice versa.

Cloning-Using the DNA of one animal to another animal with the identical genetic makeup.

Manipulation-The changing of animal DNA.


Genetic engineering in animals is a very new science. It was always a possibility but was not a feasible scientific technology. However, there were many circumstances that took into account the ethics involved and introduced people, scientists and non-scientists alike, to the field. Generally animal valves and tissue have been used in humans. Humans have successfully received pig valves and hearts. The genetics involved with this were much simpler and the scientists learned by what worked, they did not know exactly why things worked. It turns out the DNA of pig heart valves was similar enough to humans that they were interchangeable under some circumstances. The next step, which has not yet reached the stage of clinical trials, was to make pigs grow human hearts that were coded by the DNA from humans.

Cloning in animals can be accomplished by inserting the DNA of one animal into the fetus of the same specie along with a vector which gets cleans out the DNA already in the embryo. Sometimes the vector does not get rid of the original DNA of the fetus or the fetus does not adopt the new DNA. It took 277 attempts for the scientists to clone Dolly from the skin cell of a six year old. This shows some of the shortcomings of cloning that are likely to change with time. Currently scientists have trouble cloning embryos without miscarriages. The embryos that do take to the new DNA also have a greater likelihood of mutations. An additional problem stems from the fact that the cells come from other animals. Dolly's DNA came from a six year old lamb. Now some of the worries, based on chromosome tests of Dolly's cells, relate to the fact that while Dolly is only one year old some of her chromosomes have mutations that are common in much older sheep. This means that while Dolly is only one year old she may also have cha racteristics or cells that are seven years old. There are also questions about whether or not the cloned animals will be fertile. Dolly is almost old enough to reproduce now and this will be one test of whether or not cloned animals can be fertile. However, scientists will still want to look at a larger sample size before they decide whether or not cloned animals are infertile.

There have been other instances where animals have been successfully cloned. Cloning has great potential as a money making industry and also in producing genetically identical animals for testing. Much of the cloning research in animals thus far has been focused on cattle. There would be great demand for a technology that could reproduce the best cows (produce the most milk, or meat, etc.) quickly and cheaply.

Gene Manipulation

Thus far the scientists have had bad results trying to manipulate animal genes. There have been good results but many of the studies are still pending. One successful attempt has been the engineering of a pig to produce human insulin that can be used to treat diabetes. Research is also being conducted at both Dartmouth and Duke University over using pigs hearts that have enough human characteristics to keep from being rejected by humans. These pigs would be used for heart and valve transplants. Some of the problems are the difficulty involved with doctoring the genes of a higher level organism and the differences that still exist between humans and animals. Even once pig hearts can be used in humans they will still have a different circulatory system and life expectancy to contend with among other problems.


Xenografting is generally the use of DNA between both human and animal organisms. Since xenografting deals with both human and animal biology there are ethics involved with both groups. This kind of research and development has great potential as a money making device, a research tool, and in medicine. There are decisions that need to be made about how far reaching xenografting and the genetic engineering of animals my reach. On a larger scale there are also questions about genetic engineering as a whole.

Xenografting gives animals human DNA and vice versa. If an animal has human DNA is it still an animal? Would you want to eat a chicken with human DNA?

Animals are one "step" down the ladder from humans. Where is the line drawn? Should there be bleeding between the two groups?

What are the current and potential benefits that make genetic engineering of animals worth while?

How does the chemical based genetic modification differ from the age old process of selective breeding?

Should companies be allowed to patent the genetic modification of an animal? If not, what steps can they take to protect their research?

There are endless amounts of questions involved in genetic engineering in general but I think the decisions are particularly jarring with animals because they are very similar to humans; more so than plants. Are humans ready to handle a future where their bloodlines may include animal genes from someone who got a pig/human heart transplant?

For genetic engineering of animals to be useful and practical humans must come to grips with coming into contact with animals that contain human genes and vice versa. There may be humans with pig hearts in the very near future. There are also risks associated with any kind of genetic engineering, but if society can agree with it on a basic level it will lead to a lot of good. There is a huge amount of money invested already and even more waiting for a chance. Genetic engineering is the thing of the future. Religious beliefs may be tested, genetic engineering of animals may not be part of the future, but in some form genetic engineering as a whole will have a profound impact on our future.

Once genetic engineering of animals is accepted a big issue is the relationship between science and money. Genetic engineering is advancing thanks to the large amounts of green given by corporations who see it as an investment. If they can increase milk production in cows or make animal/human organs that are not susceptible to rejection they will be rich.

Conflicts Between Industry and Medicine

The battle is between private investments and other money, government and private, looking to advance the science. On one hand genetic engineering of animals has great promise. It could solve the shortage of organs which kills thousands of people each year as they wait in line for an organ they may receive too late. This is something that has great promise as an investment and an asset to society. There are other more short termed money making research projects that debase the scientific community and hurt the welfare of society. These are things associated seldom with the medical field but more often with production. For example the use BGH (Bovine Growth Hormone) in cows to increase their milk production. This was not an medical concern and it has few benefits, except for cutting down on grazing land, but enough milk was already being produced. These production minded projects taint the medical promise of genetic engineering and turn it into a dangerous money making scheme. There are many risks associated w ith genetic engineering. It is a field that is not completely understood and there are many risks involved; disease (both for one generation or genetically based), infection from animal genes, and a restriction of the genetic base (like inbreeding) with more to come. Genetic engineering will be a part of our future and DNA from non-human animals has already been useful. Soon this explosive new industry will find its limits within society's moral's.

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