Animals are used for lots of things. It could be a dietary/nutritional study, psychological and behavioral study, drug development, etc.
Many important drugs we take were developed through animal research. And if your own pet dog or cat is sick, and a vet prescribes a drug, surgery, or other therapy, that will have been tested/developed using animals, too.
Actually the point I was trying to make is are they possibly infected with some virus that could be passed on to humans. If not, why issue directives for folks to stay inside and keep house closed up.