Korpen are the beasts of burden in the Dragons' Geas series. Think giant Rhinoceros Beetle, add some spikes on its back, and you would be close. They are very large pests. Gentle and easily distracted by food, yet if they wander as a herd onto a farm, devastating to the farmer. They first appear in the novel Outcast.
Excerpt from outcast:
Korpen had originally been slow moving pests that roved in herds and a nuisance to outlying farms. They were single-minded when hungry despite their slow moving methodical pace. In untamed areas, korpen were wild and yet still would let you walk right up to them as they ate. Taming them was easy if they knew that a source of food awaited them. Their massive heads had double horns that were oriented vertically. The upper horn curves forward from behind the head, whereas the lower emerges from the head itself. As a protection from predators such as dragons, their back’s spikes were almost impenetrable. It was useful to the miners as korpen were strong and a great amount of weight could be attached to each spike.