Biology was my favourite science in high school. I took it all the way through to grade 12. I dissected octopuses, baby pigs, and
sharks. Each time I thought it was really interesting. I'm also a vegetarian. If no one's gone out and shot dead an endangered species or by any other means killed the specimen (at least in a way it wouldn't have been killed anyway), then I really don't have a huge problem with it. Dissection is an important method of learning about species, and in the case of humans, learning about ourselves. I'd much rather have a specimen be used for science than be eaten.
Also, I was never forced to do dissections. The octopus was in grade 8, and you could opt out of it. The pig and shark were in grade 11 and 12 biology, which were not mandatory for students (unless you needed biology for post-secondary, in which case you should start getting used to dissections).
Does anyone watch
The Brain Scoop? It's a really cool educational show about biology and ecology, centred around the Field Museum in Chicago. They cover a whole range of topics, but most famously they've done several episodes on dissection. They've dissected a two-faced calf, a wolf, an anteater, a really gnarly squirrel, and maybe a couple of others. (All the videos with gross stuff in it have a warning at the beginning).
Some fantastic advice on dissection: