"Every day some animals become weak and ill and enter a process of dying that involves prolonged pain as far as we can judge from their behavior. When wild reindeer smell large carnivores like bears, wolves, or dogs, they run away quickly. Old and tired reindeer find it more and more exhausting to keep up with the others. The same holds of some of the young ones. If they are caught quickly by carnivores, they tend to get a rapid, merciful death and not a slow, "cruel" one. Some reindeer experience the latter. Having been badly attacked by a winged insect (Cephenomyia trompe), they may die very slowly from suffocation from the growing larvae in their noses."