I think that oversimplifies it. One approach is use animals early because if there is no effect in animals, then you don't have an effect.
Once you have an effect, use in vitro models/cell culture to figure out potential mechanisms, then test again in animals to confirm.
If you are doing a PhD (or whatever), do you want to spend 5 years not knowing if your discovery only works in test tubes?
> reasonable confidence the risk and severity of harm from the testing will be minimal
this sounds good, but how do you actually define that? how harmful do you consider giving an animal a UTI (which has the chance to infect kidneys, etc if untreated)?
> For test animals that are or aren't harmed, allow them to live happy, (relatively) normal, natural lives
I agree on principle but for infectious disease you can't really do this without potentially releasing lab strains into the wild.
Something you didn't mention would be to try to use as many parts of an animal that you sacrifice as possible, but then again you're just cluttering expensive -80C freezer space with random tissues if you don't use them. But sometimes when doing ex vivo experiments you can turn one mouse intro multiple samples if you cut the tissues up and expose each one to different conditions, rather than treating the whole mouse. That can save mice..
Once you have an effect, use in vitro models/cell culture to figure out potential mechanisms, then test again in animals to confirm.
If you are doing a PhD (or whatever), do you want to spend 5 years not knowing if your discovery only works in test tubes?
> reasonable confidence the risk and severity of harm from the testing will be minimal
this sounds good, but how do you actually define that? how harmful do you consider giving an animal a UTI (which has the chance to infect kidneys, etc if untreated)?
> For test animals that are or aren't harmed, allow them to live happy, (relatively) normal, natural lives
I agree on principle but for infectious disease you can't really do this without potentially releasing lab strains into the wild.
Something you didn't mention would be to try to use as many parts of an animal that you sacrifice as possible, but then again you're just cluttering expensive -80C freezer space with random tissues if you don't use them. But sometimes when doing ex vivo experiments you can turn one mouse intro multiple samples if you cut the tissues up and expose each one to different conditions, rather than treating the whole mouse. That can save mice..