What is ethical treatment of animals?

Today, in the PSYCH 261 lecture, the prof discussed research ethics. It was interesting to hear about some of the cases that prompted the whole concept of research ethics. For example, the Nazis performed horrific experiments on prisoners, and some labs have been charged with mistreating animal subjects. For example, the image below was part of a photo-essay in Life magazine in 1966.

©1966 Stan Wayman/Life

It prompted the Laboratory Animal Welfare Act of 1966, which regulates the sale of animals for research use, as well as enforces a minimum standard of care for laboratory animals.

When it comes to seeing an animal suffer, I'm just as squeamish and sympathetic as the next guy. But the whole discussion got me thinking. What does it really mean to suffer? What, exactly, is it that we're trying to accomplish with these regulations?

I'm totally on-board with preventing people from stealing family pets to sell them to labs. No issue there. What I'm confused about is the requirement that laboratory dogs should be allowed to exercise, and non-human primates be afforded "environmental enrichment". Is there a rationale for this? Or has science been hijacked by our human tendency to sympathize? After all, many species kill, dismember, paralyze and consume each other without any legislation at all. Is bacteria less alive than a monkey? We kill bacteria every day.

[From intelligent-falling.blogspot.com]