Reply To: It should be legal to eat dog and cat meat.

Scientists would not want to use random animals from a shelter for medical experiments- too many variables, too many differences that will distort the results and make it impossible to interpret the outcome of the experiment. Did Fluffy live longer than Fido after taking medicine X because medicine X worked, or because Fido was weaker after living on the streets for 2 years?
Scientists who use animals like mice and rats use ones that are bred for that purpose- their genetic background is known and the same in all animals used for the experiment, they are matched by age and often gender, they are kept in sterile, germ free housing, they are fed the same food, have the same day/night cycles, etc. Research with larger animals is rarer, mostly because they take longer to breed and are more expensive to keep, and are not as practical, although sometimes it is necessary to use a larger animal more similar to a human, like monkeys for neuroscience research.