In my understanding, they are pretty harmless and rarely kill their host unless they are in a part of the body where it would kill them. If they are under the skin close to the surface it wouldn't kill the animal, but if the eggs are ingested and they hatch inside it is a different story.
Here's a gross post of a rabbit (still living) who had one in its nasal cavity if anybody can stomach pictures.
http://www.goosemoose.com/component/...opic,4024579.0
