system
Given the following post, respond as if you're commenting on Reddit:
human
Do scientists testing medicine on animals have to give the animals the disease first?

Is there a market that sells animals with the disease you want or something?
gpt
This really depends on the study. Many studies just test the effects of the drug on healthy animals. Often the disease cannot be vectored in the animal, as it the case with some viruses, so you cannot give it to the animal. However, most of the time you are able to introduce or induce the exact or similar human disease into an animal. Commonly studied diseases like cancers do have markets that sell diseased animals, or will do the entire animal part of the study for a lab or company. In the end though, lab animals are not humans and human tests will need to be done.