Genetic engineering of animals: ethical issues, including welfare concerns.

The genetic engineering of animals has increased significantly in recent years, and the use of this technology brings with it ethical issues, some of which relate to animal welfare — defined by the World Organisation for Animal Health as “the state of the animal…how an animal is coping with the conditions in which it lives” (1). These issues need to be considered by all stakeholders, including veterinarians, to ensure that all parties are aware of the ethical issues at stake and can make a valid contribution to the current debate regarding the creation and use of genetically engineered animals. In addition, it is important to try to reflect societal values within scientific practice and emerging technology, especially publicly funded efforts that aim to provide societal benefits, but that may be deemed ethically contentious. As a result of the extra challenges that genetically engineered animals bring, governing bodies have started to develop relevant policies, often calling for increased vigilance and monitoring of potential animal welfare impacts (2). Veterinarians can play an important role in carrying out such monitoring, especially in the research setting when new genetically engineered animal strains are being developed. Several terms are used to describe genetically engineered animals: genetically modified, genetically altered, genetically manipulated, transgenic, and biotechnology-derived, amongst others. In the early stages of genetic engineering, the primary technology used was transgenesis, literally meaning the transfer of genetic material from one organism to another. However, with advances in the field, new technology emerged that did not necessarily require transgenesis: recent applications allow for the creation of genetically engineered animals via the deletion of genes, or the manipulation of genes already present. To reflect this progress and to include those animals that are not strictly transgenic, the umbrella term “genetically engineered” has been adopted into the guidelines developed by the Canadian Council on Animal Care (CCAC). For clarity, in the new CCAC guidelines on: genetically-engineered animals used in science (currently in preparation) the CCAC offers the following definition of a genetically engineered animal: “an animal that has had a change in its nuclear or mitochondrial DNA (addition, deletion, or substitution of some part of the animal’s genetic material or insertion of foreign DNA) achieved through a deliberate human technological intervention.” Those animals that have undergone induced mutations (for example, by chemicals or radiation — as distinct from spontaneous mutations that naturally occur in populations) and cloned animals are also considered to be genetically engineered due to the direct intervention and planning involved in creation of these animals. Cloning is the replication of certain cell types from a “parent” cell, or the replication of a certain part of the cell or DNA to propagate a particular desirable genetic trait. There are 3 types of cloning: DNA cloning, therapeutic cloning, and reproductive cloning (3). For the purposes of this paper, the term “cloning” is used to refer to reproductive cloning, as this is the most likely to lead to animal welfare issues. Reproductive cloning is used if the intention is to generate an animal that has the same nuclear DNA as another currently, or previously existing animal. The process used to generate this type of cloned animal is called somatic cell nuclear transfer (SCNT) (4). During the development of the CCAC guidelines on: genetically- engineered animals used in science, some key ethical issues, including animal welfare concerns, were identified: 1) invasiveness of procedures; 2) large numbers of animals required; 3) unanticipated welfare concerns; and 4) how to establish ethical limits to genetic engineering (see Ethical issues of genetic engineering). The different applications of genetically engineered animals are presented first to provide context for the discussion.

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