When I was in high school Biology I, we had to dissect frogs that arrived in big vats of formaldehyde. It was not pleasant, but it was kind of like cutting up a rubber toy. Nothing about those frogs was remotely lifelike. I did it, because this was in the 80's, and I had no clue that you could opt out of things like that. Everyone bucked up and did it. It wasn't that bad, really.

Now, when I took advanced Biology II in high school, we had to dissect live frogs. We pithed them, and cut them up. It was HORRIBLE. I am still tormented by that, twenty years later. If I thought by any remote chance that I could have gotten out of it, I would have tried. Some people cried, some people threw up. Didn't matter, everyone had to do it.

I learned NOTHING from the experience, because it upset me and grossed me out completely. I was too tortured to learn. It did me absolutely no good to kill that frog. However, I was an accounting major in college, not pre-vet. There IS value to dissection, for pre-vet or pre-med students. Just not your average high school kid.

As for dissecting a cat or dog that has already been euthanized .... frankly, I have far less of a problem with that than killing a frog or a rat or even an earthworm simply for the purpose of having high school kids dissect it. The cat or dog was killed due to over-population, over-breeding and throw-away attitude. If it's body is dissected afterwards, there is no more harm done. Dead is dead.

Let's not miss the forest for the trees here - the cat is dead because someone didn't spay or neuter their pet, let them run loose, wanted their kids to see the "miracle of birth", wanted a kitten from the litter, got tired of their old cat and took it to animal control, etc. etc. etc. The cat is not dead because of a high school biology class.