olls, egg cartons, and PVC tubing can provide rodents with places to hide. Bales of straw and rubber tires can be used to create an area for rabbits to interact with other members of their species. Dogs can be given numerous toys to play with, and be provided with a raised platform so they are not forced to stand in their own waste.It is also important for the staff of the facility to be well trained in handling the animals that are being used, and that they have the correct attitude when working with the animals. Anesthesia should be used whenever possible, and at the end of the experiment, the most humane method of euthanasia should be chosen.The final concept of the three Rs is replacement. Any experimental system that does not use whole, living animals is considered to be a replacement alternative. Some of these techniques still involve the humane killing of an animal for the purpose of obtaining cells, tissues, or organs for in vitro studies. Other techniques involve no use of any biological material from a fully developed vertebrate, non-human animal. In some cases, replacement methods can be used for the total replacement of animals in a study, in others they will complement animal experiments and reduce the total number of animals used in the whole project. Replacement alternatives can be divided into six categories: information; computer-based systems; physico-chemical techniques; the use of lower organisms and embryo stages; human studies; and cell, tissue, and organ cultures (5).Access to information can prevent the unnecessary duplication of animal work that has already been done. Also, the in vivo data that has already been found to be reliable can be used to validate alternative methods without having to do any new animal studies. Developments in computer modeling and expert systems that can predict biological activity and toxicity have already revolutionized the process of drug development by eliminating the nee...
