Are the animals used in dissections, (piglets, cats, frogs, etc) dead before the dissection or are they killed?
In dissections at the high school level all of the animals used are dead.
No animal is alive during a dissection (at the high school level), animals are typically killed and sold as specimens for dissection however most of these animals are not killed for the sole purpose of dissection. The animals used for dissection are typically seen as a by-product of an industry.
Animals that we view to be domesticated such as cats or dogs usually come to shelters as feral animals. In order to prevent the unjustified euthanization of an animal, most states must keep an animal at a shelter for 5 days (in some states its longer) if they don't have a microchip (if they are chipped the owner must be contacted to come an retrieve the animal), before the animal can be euthanized. If the animal is euthanized instead of discarding the body (via cremation) the shelter may opt to donate (never sell, that's illegal) the body to a supplier or school.
It is more than likely that the pigs used for dissection in schools are fetal pigs (they were never breathing oxygen on their own), the parent pigs were raised on a farm (with the intent of entering the food supply), if it turns out that a pig is pregnant when they are killed the "baby" pig is removed and instead of discarding the baby (which hasn't been fully formed) they sell it to a dissection supplier for use in schools.
Frogs, unfortunately, are usually captured for the sole purpose of becoming a dissection specimen.
Sometimes small sharks are used a in dissection (mainly for marine biology students) these sharks accidentally get caught in a fisherman's net and die (sharks need keep moving to have water flowing over their gills in order to breathe). These sharks, if they're small enough, can be sold to dissection suppliers rather than being discarded.
If you are a K-12 student in the U.S., have ethical concerns about dissection in your school, and live in one of the 18 states listed below, you can always opt out of the experiment without being penalized (your teacher will give you a different assignment to do).
States with Student Choice Laws:
- New Hampshire
- New Jersey
- New Mexico
- New York
- Rhode Island
On a lighter note: unicorns and rainbows!
Image Courtesy: Zakeena (sketchport user); Obtained from: https://www.sketchport.com/drawing/6326943955812352/pink-blurry-unicorn-under-a-rainbow; Reused under: CC-BY
I hope this helps!