A necropsy is an examination or autopsy performed on an animal that has died. This is different from a postmortem exam, which would be done on a human.
When we talk about a necropsy, it's usually because someone wants to understand what caused the death of the animal. For example, if you have a pet that passes away unexpectedly, a vet might do a necropsy to figure out what went wrong. This can help them make sure other animals in your care are safe from similar problems. If you're involved with an organization that works with endangered species, they might also use necropsies to learn more about how those animals died and find ways to protect them better.
(medicine) The pathological examination of a corpse, particularly to determine cause of death.
