I can respect your point. Quite honestly, I don't know where the dogs come from.
However, what I really have a problem with is that a small minority of people who have objections to the lab (and who can opt out), are trying to take it away from people who want to participate in it. If the way the dogs are being obtained is the problem, why not work to ensure they are from a reputable source, rather than to take away what I personally consider a valuable learning experience.
Personally, the lab was one of my favorite experiences of my first two years. Yes, I agree that the material is covered in several different ways, that there is a computer simulation, and that we didn't generate any new knowledge. But I felt that I learned new things during the lab. I personally learn more by doing, and am grateful for the experience. For me, the argument that you can learn the material from a book or simulation doesn't hold any water at all, because by the same logic, you could replace the third and fourth years of medical school with more books and additional simulators (like the surgery or anesthesia sims).
As far as the lab contributing to higher grades, or board scores, or whatever, that's all irrelevant. A person should be able to learn/master the material in the best way for them. This is a very individualized issue, and for me, the dog lab cemented several concepts, and contributed to my personal learning experience. This is why I have a problem with people trying to force their personal beliefs on others by trying to take it away. The option for you to opt out is there, and will continue to be. The option for me to opt in should also continue to exist, because we each learn best in our own way.